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satisfied that British lamps were efficient, professedhimself willing to discuss the matter with representa-tives of the miners in the Ilouse. Eventually thedebate was adjourned.The recently issued report on miners’ nystagmusl

contains a criticism (p. 38) which probably refers to thetransition period before the British manufacturershad undertaken to pay special attention to the matter :"

During the war years the lamp-glasses supplied tothe lamp-makers have been of an inferior quality andfull of flaws which broke up the field into blotchesof irregular light." As to the increased number of casesduring 1919 and 1920, the Committee attributes thispartly to an accumulation of long-standing cases andpartly to a recertification or resumption of payment tomen who had failed after return to work. The numberof men who show nystagmus on examination certainlyvaries in different countries and also with the observer.For example, Sir Josiah Court, in a report to the Derby-shire Miners’ Association in 1891 gives the percentageas 34.75 of all coal cutters examined, whereas Llewellynin 19122 gives it as 22. The incidence of a disease ofsuch complexity wherein there is so large an elementof psychoneurosis, is always difficult to assess.

TREATMENT OF HÆMORRHAGE FOLLOWING

TOOTH EXTRACTION.

IN the Revue de Stomatologie (January, 1922) Dr.Th6s6e gives an account of a boy, aged 10 years, whosuccumbed to haemorrhage following the removal bythe boy himself of a right lower second deciduousmolar. The roots of the tooth were completelyabsorbed and the child pulled the tooth away withhis fingers. The attention of the parents was drawnto the bleeding on the third day; pressure was appliedto the bleeding area and injections of haemostyl weregiven. The haemorrhage continued, with remissions.The child was admitted to hospital and gelatin serum i

was injected, but his life could not be saved.Haemorrhage after the extraction of teeth may be

serious, and since the patient may not take alarmuntil several hours have elapsed, it often becomesthe duty of the nearest available doctor to treat thecase. Plugging the socket. providing it be accuratelyapplied, will generally suffice but may not be easy,and many styptics have been recommended as anadjuvant. Some of these, for example ferric chloride,give rise to subsequent sloughing, which more thanoutweighs their haemostatic action and are thereforeto be condemned ; others, like adrenalin, are so

quickly diluted by saliva or blood that they becomeineffective. Mr. F. St. J. Steadman. in an interestingpaper read before the Section of Odontology of theRoyal Society of Medicine, and published in theBritish Dental Journal for April 1st, advocates the useof oil of turpentine and states that over an experienceof 12 years he has not known it to fail. The method ofapplication is simple. The gauze is soaked in the drugand the socket packed ; if necessary it is kept in placeby stitching or by applying a pad over the gum andbandaging the jaws. Mr. Steadman gives notes offour cases in which the hæmorrhage was severe. Thepatients were all women and in each there was ahistory of a liability to bleeding ; the father of onepatient had died from hæmorrhage. The teeth wereremoved at intervals with great care and all went welluntil a canine was extracted. This bled profusely forseveral hours. The socket was syringed with cold waterand packed with gauze soaked in oil of turpentine,.and the bleeding ceased immediately. Another patient,a woman of 30, gave a family history of a mother witha tendency to bleed, the patient’s son died of haemor-rhage after circumcision at the age of 4, and herdaughter also had haemophiliac tendencies. Severalteeth were extracted without any bleeding, but profusehaemorrhage followed the removal of a molar. In this,case it was necessary to pack the socket on three

1 See THE LANCET, April 29th, p. 854.2 The Colliery Guardian, 1912.

occasions before the bleeding was finally controlled.Mr. Steadman remarks that although they were nottrue haemophiliacs, yet there was an abnormal tendencyto bleed in each case, so that the test of the efficacy ofturpentine as a local haemostatic was severe. In each ofthese cases calcium lactate had been given previously,but in the majority of Mr. Steadman’s cases calciumlactate was not given as the bleeding was unexpected.Mr. Steadman adds that oil of turpentine is a powerfulantiseptic, and that after the plug is removed thesockets retain a faint smell of turpentine and are cleanand free from infection. This is in striking contrast tothe usual experience after plugging, when the socketis generally septic and takes a long time to heal.

Oil of turpentine would appear to possess definiteadvantages over most other methods of dealing withhaemorrhage of dental origin, though in the BritishDental Journal for March, 1920, a case was reportedin which death resulted eight days after the removal ofthree teeth ; turpentine was used locally as advised byMr. Steadman, but even with transfusion of blood failedto save the patient. Mr. Steadman does not claimto have originated the use of oil of turpentine. It is,in fact, a very old method which has dropped out ofrecognition, although it still has an oral currencyamong older practitioners. S. J. Salter, in 1874,quotes John Hunter as advocating its use after dentalhaemorrhage and there can be no doubt that it hasproved a useful addition to the list of reliable localhæmostatics.

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THE WAR OFFICE INQUIRY INTO

SHELL-SHOCK.

THE War Office Committee of Inquiry into Shell-shock held its fortieth meeting on May 10th, LordSouthborough presiding. The Committee has finishedtaking evidence, having had the benefit of the adviceof a large number of experts, both military andmedical. and is now considering the report. It isexpected that the report will deal in detail with theorigin and nature of shell-shock, and will suggestmeasures which may be expected to mitigate theincidence of this group of nervous and mental disordersin future wars, and also measures for the treatment ofpatients suffering from such disabilities. Shell-shock,in this last connexion, need not be taken as implyingonly shock from subjection to the risk of explosivemissiles, and the findings of the Committee are sure tohave valuable messages to medical men in the conductof civilian practice, especially where that practice ismainly in industrial circles.

BLOOD-PLATELETS IN RELATION TO

A-VITAMIN DEFICIENCY.

IN our correspondence columns last week Dr. S.Monckton Copeman set out the ingredients of a dietfree from A-vitamin, the possible influence of whichon patients suffering from malignant disease is beinginvestigated. It will be interesting to note whetherthe diminution of the number of blood-plateletsobserved by W. Cramer, A. H. Drew, and J. C.Mottram in the rat on a diet deficient in A-vitamin isnoticeable in the human subject. ’ In a paper com-municated to the Royal Society on May 4th theseinvestigators record that the absence of the fat-solublevitamin from the diet always leads in the rat to aprogressive diminution in the number of blood-platelets. This thrombopenia is the only constantlesion which has so far been found in every case ofA-vitamin deficiency, and is regarded by the authorsas the lesion characteristic of this deficiency, just aslymphopenia is characteristic of the B-vitamindeflciency.l Thrombopenia may even be found in ratskept on an A-vitamin free diet, when they do not yetshow any obvious signs of ill-health and are to allexternal appearances normal animals. When profoundthrombopenia has been established, addition of the

1 THE LANCET, 1921, ii., 1202.

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missing A-vitamin to the diet is followed by rapidincrease in the number of platelets up to the normal,provided that the animal has not been allowed tosuffer too long and too severely from deficiency.Exposure to radium produces not only lymphopenia,but also, with sufficiently large doses, thrombopenia.From this the animals recover rapidly, if the applica-tion of radium is discontinued and the dose has notbeen too large. If, by exposure to radium, or bywithholding the fat-soluble vitamin, the number ofplatelets has been reduced below a certain criticallevel-about 300,000 for the rat-the resistance ofthe animal to infection is greatly diminished and infec-tive conditions develop spontaneously. These maylead to a secondary anaemia. The infective conditionsmay clear up again as the number of platelets is madeto increase. The authors claim that blood plateletsfulfil an important function in the mechanism ofresistance to bacterial infection, and that alterationsin local or general resistance to infection are associatedwith local or general changes in distribution of theplatelets.

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DYNAMICS OF MYOGENESIS.

UNDER the title of "Studies in the Dynamics ofHistogenesis," Eben J. Carey raises a very interestingquestion as to the tension of differential growth actingas a stimulus to myogenesis, and illustrates his viewsby observations on the experimental transformationof the smooth bladder muscle of the dog, histologicallyinto cross-striated muscle and physiologically into anorgan manifesting rhythmicality. In previous com-munications the author, basing his views on embryo-logical observations, was led to the view that theundifferentiated mesochyme cells in consequence ofthe influence of varying optimum tension acting onthem from without, can be transformed into differenttypes of muscle cells. So far as histological structureis concerned, there are many modifications in theform of the typical fusiform smooth-muscle type ofcell-for example, its tripartite form in the frog’sbladder and the branched ends in some blood-vessels.The heart fibres in the frog retain the fusiform shapebut are cross-striated ; the heart fibres of a mammalretain many of the characters of a syncytium, thecross-striation being perhaps a morphological changefacilitating rapid change of form resulting in a rapidmechanical response. The various types of musclecells found in the body-smooth, cardiac, andskeletal-are believed to be resultants of differentdegrees of optimum tension, the essential differencephysiologically being their capacity for work, whichin turn is dependent on the amount of work that hasbeen expended in their production. The authorexemplifies his views by comparing the heart and thebladder. At the thirtieth hour of incubation in thechick embryo the primitive mesenchyme begins topulsate rhythmically, at first slowly, then more andmore rapidly as growth continues and as the vascularchannels become hollowed out and continuous. Thisis concomitant with a constantly greater increase inthe volume of blood. The rate of the heart beatincreases from 10 to 15 at the thirtieth hour to 150to 190 per minute at the ninetieth hour. From thefortieth until the one hundred and twenty-fifth hourthe heart is composed of cells not unlike smoothmuscle, but at about the one hundred and twenty-fifthhour cross-striation appears. The author supports histhesis of the transformation of smooth muscle into thecross-striped form by experiment on the bladder ofthe dog, by converting it physiologically into an organmanifesting rhythmicality. A silver drainage-tube was Iintroduced and fixed through a suprapubic openinginto the bladder of a puppy bitch four weeks old.The fluid used was a saturated solution of boric acidat 375° C. At first the amount introduced was small- 20 c.cm. daily-but was gradually increased untilit reached 50 litres at the end of the experiment ; theanimal died on the fifty-eighth day. When the bladder

1 American Journal of Anatomy, vol. xxix., 1921.

had adapted itself to the successive introduction ofincreasing amounts of fluid, and when it was distendedto its greatest capacity, it began to beat rhythmicallyafter the manner of a heart beat, the beat varyingfrom 10 to 300 per minute according to the degree ofdistension of the organ. With every contraction of thebladder fluid was expelled through the urethra. Theexpulsion was due to vesicular contraction and notto a passive transmission through the bladder-

i.e., the contractions of the bladder musculature areactive and independent of the heart and respiratorymovements, not being caused by any indirect influencefrom the respiratory or cardiac regions. It waspossible by an arrangement described in the text soto vary the intravesical pressure as to imitate at willmany of the common phenomena manifested bythe heart-e.g., bradycardia, tachycardia, extra-systoles, &c.The changes in the bladder musculature were very

remarkable. At the beginning of the experimentthe thickness of the bladder wall when fully dis-tended was 0-5 mm., and the weight of the bladderof a similar dog four weeks old weighed 0-75 g.In the animal experimented on the bladder weighed4-75 g., while that of a control animal weighedonly 1-59 g. The musculature presented a deep redtint resembling somewhat cardiac muscle, and the wallwas 5 mm. thick and the organ was very vascular.Histologically, the network of broad fibres withcentrally-placed nuclei showed the isotropic andanisotropic cross-lines, sometimes solid, sometimescomposed of granules ; no intercallated discs, however,were seen. The transitional epithelium of the bladderhad undergone hyperplasia. The author concludesthat the differential degree of energy possessed by thetypes of muscle is purely an embryological problem,and that the essential difference between the palesmooth muscle of the bladder and the red involuntarystriated muscle of the heart is dependent upon thedifferential intensity of hydro-dynamic tensionalstimuli to which the vesical and cardiac mesenchymalsyncytia respectively, have been subjected duringdevelopment. As the result of his studies the authorclaims that he has proved that the pale bladdermusculature may be transformed into the red, cross-striated type by increasing the tensional stimulus toa degree comparable with that which the cardiacmesenchyme experiences normally. Function in thiscase, he claims, determines structure.

THE ULTIMATE PROGNOSIS IN EPIDEMICENCEPHALITIS.

THE growing conviction that epidemic encephalitisinflicts permanent injury in a large proportion of thecases which survive the acute stage of the diseasefinds confirmation in a recent paper by Prof. R. Bingand Prof. R. Staehelin in Schweizerische medizinischeWochenschrift for Feb. 9th. They have investigatedthe after-histories of their 97 patients who had sur-vived the onset of the disease by at least nine months.Only 39 were cured, and if the cases of epidemichiccough and other rudimentary forms be excluded,then there were only 24 recoveries out of 80 cases.The sequel which is most to be dreaded is a form ofparalysis agitans of which the authors distinguish twotypes, early and late Parkinsonism. Their materialincluded 36 cases of Parkinsonism, 11 of which belongedto the late type, the prognosis of which seems to beinvariably bad. This late Parkinsonism may appearmore than a year after the onset of the encephalitis,and once it has developed it invariably runs a progres-sive course. The authors were at first inclined toregard with comparative optimism the Parkinsonismwhich developed in direct continuity with thesymptoms of epidemic encephalitis, and in a tableshowing the fate of 25 such cases, one is indicated asbeing cured, and seven are placed under the heading" Improving." But in a footnote the authors statethat this single case of recovery had proved deceptive,a severe relapse having occurred. They are, therefore,