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Annotations

SULPHONAMIDES AND MENINGITIC SEQUELÆMaddock has studied sequele in 1075 patients who

recovered from cerebrospinal fever after chemotherapy.In every case the diagnosis had been bacteriologicallyproved ; the nurses of the American Red Cross HarvardUnit Hospital paid the follow-up visits and either sawthe patients or got information about them from relativesor neighbours. The time between discharge from

hospital and the visit varied from 1 month to 2 years.In all 254 (23-6%) complained of some disability datingfrom the attack. Headache was the commonest sequel,being present in 117. More serious symptoms- werefortunately rarer ; 6 had lost the sight of one eye, 1 ofboth eyes ; 13 were totally deaf -and 24 had impairedhearing. There was one case each of hydrocephalus,spastic paralysis and facial paralysis ; 10 had strabismus ;18 were said to have changed in disposition and 9 childrenwere retarded in development. Weakness of the legswas noted in 22, and muscular pains in 28. Othersymptoms included errors of refraction, nervousness,irritability, poor memory, lack of concentration, easytiring and depression. Maddock suggests that the listappears more formidable than the facts warrant, sincethese sequelae are not all necessarily permanent. Head-aches, for example, usually diminish in intensity andfinally disappear. A group of 31 patients reported tohave disabilities were fully examined by doctors 3-8months after the nurses had made their visits ; 16 ofthem had completely lost their symptoms and werein perfect health ; in 7 the sequelae reported had not beendue to the illness ; 2 had symptoms possibly due tomeningitis but beginning to clear up ; and in only 9 werethere permanent sequeloe due to meningitis. The dosageof sulphonamide bore no apparent relation to the incid-ence of sequele, and Maddock supposes that in manypatients damage to the central nervous system is

probably done at the onset of the illness and is not,affected by chemotherapy.

UNDER-WATER BLAST

AN ingenious technique has been described byAmerican workers for studying the effects of rapidcompression waves on animals submerged in water.Since the results run closely parallel to those found by anumber of observers 2 in man and animals exposed todepth charges, it looks as though the laboratory workerwere now provided, with a simple way of investigatingunder-water blast without the limitations and fuss

imposed by the use of explosive forces.- Clark and Ward 3 describe a method of subjectinganimals to shock waves in water by dropping a weighton a floating plunger. In one end of a steel TJ-tube nlled

with water or saline is loosely fitted a wooden plunger onwhich a rack carrying a falling weight, released from anydesired distance, is allowed to fall. The anaesthetisedanimal is in the other end of the U-tube, within a tubularcage of hardware cloth or, if water surging is to bewholly avoided, in a tin can, open at the top and almostfilled with water. The impact so produced sets upwaves very like those generated by setting off an explo-sive under water, with primary " compression " wavesof extremely short duration (1/5000 sec.) and no surgeof water such as occurs when the gases of an explosiveexpand. By varying the weight on the rack and thedistance of fall a great variety of lesions may be produced.Under extreme conditions the animals are killed in a fewminutes ; with lighter impacts they survive longer orrecover completely. The immediate effect is a rapidslowing of the heart-rate and cessation of respiration1. Maddock, E. C. E. Bull. Min. Hlth & EPHLS, 1943, 2, 1112. See Lancet, 1943, ii, 133.3. Clark, S. L. and Ward, J. W. 1943, Surg. Gynec. Obstet. 77, 403.

for a few seconds to more than a minute, followed by, laboured and ineffectual respiratory movements. Intra-

pulmonary bleeding sets in at once and may lead toearly death. Although occasional animals show loss "

of corneal reflexes, ataxia and incoordination immedi-ately after the blow, direct involvement of the centralnervous system is exceptional and electro-encephalograms.provide no evidence of concussion at the time of theimpact. Autopsy findings in these animals are identicalwith those described by Cameron, Short and Wakeley *and Williams 5: they include massive pulmonaryhaemorrhage, bruising and haemorrhage in the stomach"lower ileum and caecum, with occasional rupture ofstomach or intestines and haemorrhage into the peri-toneal cavity or lumen of stomach and intestines. Aspointed out by the British workers, the solid viscera, "

in contrast to air-containing cavities, rarely show damage.Some of Clark and Ward’s conclusions may be briefly

summarised. The greater the impact, the more damageto the animal ; the larger the animal the less theeffect for a given impact. The more hunched-up theanimal is in the water, the less seriously is it affected.With incomplete submersion, only that part of theanimal below the water level at the time of impact shows.the typical lesions. (The work of Cameron, Short andWakeley,3 does not, however, bear out this conclusion.)Damage is greater to fully inflated lungs than to deflatedlungs. Protective coverings, such as cork or spongerubber life-preservers, save the regions covered frommuch of the effect of an otherwise fatal blow.

PREDETERMINATION OF SEX

FLUCTUATIONS in the sex ratio during war, discussedby ’Dr. Martin on p. 807, remind us how little influencewe have with our posterity, even at the outset. Only inthe present century has the mechanism of sex-determina-tion been elucidated. Basically it is simple enough inman. The sex-chromosome pair in the female somaticcell consists of two equal members, the x-chromosomes.The male somatic cell, on the other hand, contains anunequal pair, consisting of one x-chromosome and asmaller Y-chromosome. When the gametes are formed,’

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the members of each chromosome-pair separate, so-thatwhilst all ova contain an x-chromosome, half the sper-matozoa contain an x-chromosome and half a Y-chromo-some. Should it chance to be an x-bearing sperm whichfertilises the ovum, the result is a girl ; should it be a

Y-bearing sperm, the result is a boy. Many other livingthings exhibit an identical or very similar mechanism.It is not always, it is true, quite as simple as the schemejust outlined, but in no case can the primary determine-tion of the sex of the new individual be termed reallycomplicated.

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It is one thing, however, to understand how a mechan-ism operates and quite another to control it. Manypossible approaches have been attempted, though nearlyalways with negative results up to the present. The dayis probably far off when the sex of the future child can bedetermined at will-or indeed’ materially influenced-in the desired direction. It has been shown, however,in animal experiments that a tendency to produce anexcess of females or of males may be to some extentgenetic ; and generations of selective breeding can onoccasion produce strains which do yield some preponder-ance of one sex or of the other. Furthermore, in droso-phila much more definite means of predeterminationhave been demonstrated. Lethal genes have been-discovered which are sex=linked and by introducing theminto the x-chromosomesby breeding methods it is possibleto ensure that some at least of the xy individuals, themales, do not develop. In fact, by utilising in additiongenes which inhibit crossing-over (that is, the interchange4. Cameron, G. R., Short, R. H. D. and Wakeley, C. P. G. Brit. J.

Surg. 1942, 30, 49 ; 1943, 31, 51.5. Williams, E. R. P. Ibid, 1942, 30, 38.

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of genes between members of a chromosome pair) it ispossible to produce strains which yield J 00% females.

Recently, Gowen and Nelson 1 have announced theproduction of a strain the females of which produce100% males, irrespective of the males to which they aremated. This result is due to a dominant gene whoseaction is limited to the female sex. Thus in drosophila,in one sense, complete sex-control is possible : stockscan be bred which yield offspring of one sex only, eitherfemales or males at will. The discovery of course canhardly be said to have any application to man. Thisis no simple matter of an injection or a pill, ensuringthe arrival of a baby of the required sex. It hardlystirs the pulse to be told that some day, if the appro-priate genes happen to be discovered in man, it mightbe possible after many generations of selective breedingto -produce women whose fertilised ova of one sex orthe other would die at a conveniently early stage.Primitive peoples, who eliminate unwanted babies assoon as they are born, would :hardly regard the methodas a practical advance.

ORIGIN AND PATTERN OF RETINALHÆMORRHAGE

WHAT determines the distribution of retinal hoemor-rhages in vascular disease and what is the anatomicalreason for their pattern ? In his Montgomery lectureto Irish surgeons Ballantyne 2 gives an answer tothese questions based on ophthalmoscopic and micro-scopical findings. Three common causes of retinalvenous haemorrhages are choked disc, subarachnoid

haemorrhage, and thrombosis of the central retinal vein.The immediate cause of the haemorrhage in all three is theobstruction to the outflow of blood from the retinal veins,and yet the distribution of the haemorrhage is different ineach case. Ballantyne explains that in healthy blood-vessels extravasation of blood through the vessel wallsfrom back pressure will be chiefly where the vesselchanges course or where it receives increased or decreasedsupport from surrounding tissues. At the optic disc thevessels both change their course and lose support, so thatwhen pressure suddenly rises, as in choked disc, thehaemorrhages will be situated at and around the disc.In subarachnoid haemorrhage the rise of pressure is mostsudden, and here the haemorrhages arise not only in theretina around the disc but also in the orbit where thereis lack of support for the vessel wall. Thrombosis of thecentral retinal vein causes widespread venous hoemor-rhage throughout the retina. Here, while the actualblockage has been sudden, this is only the final phase ofa progressive obstruction. The vein behind the laminacribrosa has been gradually narrowing, and the circula-tion in the vein getting slower, with the result that thevein walls suffer from anoxoemia and become devitalised.At the moment of final obstruction the pressure,. actingon the weakened walls, causes haemorrhage throughouttheir length. The exact source of a small retinal haemor-rhage can often be estimated by closely observing itsshape. Such haemorrhages are chiefly found in the inter-vals between visible retinal vessels, which suggests thatthey are capillary in origin. An interesting picture ofcapillary haemorrhage is that in which a blood-vessel

passing through a patch of haemorrhage is accompaniedby a blood-free zone-a pale band on either side of theblood column. This blood-free zone closely correspondsto the capillary-free zone found on either side of theretinal arteries.3

It is common knowledge that striate, flame-shaped,or brush-like haemorrhages take on this form because theyare situated in the nerve-fibre layer of the retina, and theblood naturally tracks between the fibres which are herelying parallel to the surface. Such haemorrhages come1. Science, 1942, 96, 558.2. Ballantyne, A. J. Irish J. med. Sci. October, 1943, p. 551.3. Michaelson, I. C. and Campbell, A. C. P. Trans. ophthal. Soc.

U.K. 1940, 60, 71.

from the arterial side of the capillary system, and areoften seen in hypertension. Haemorrhages from thevenous side of the capillary system are usually found inthe deeper retinal layers, because the efferent veins of theretina are derived from the deepest capillary plexus.They are especially common in the outer molecular layer,where owing to the direction of the fibres the tissuestend to split in a vertical direction, allowing the h2emor-rhage, as seen with the ophthalmoscope, to assume apunctate or peteehial form. Haemorrhages of the kindare well seen in diabetic retinopathy.

AGRICULTURE AND MILK

AFTER the war this country will again import largeamounts of grain, sugar and other products more cheaplygrown abroad ; but if we are to raise the standard ofnutrition British agriculture will have to provide moreof the so-called protective foods-fruit, vegetables, eggs,and especially milk and dairy products. It does notfollow that corn-growing and the traditional feeding forbeef will fall below prewar levels ; they may be higher.Each occupies an interdependent place in a system ofmixed farming without which soil fertility ’cannot bemaintained.- .

The war-time ploughing of millions of acres of per-manent grass, much of very low quality, has producedarable crops ; but there are already indications that itmay easily lead to soil exhaustion which is being acceler-ated by the decrease in the number of livestock. Staple-don and Davies nevertheless believe that it can doinfinite good if we think in terms of sensible rotations andregrass as we go. Last year-and even more this year-there have been protests against the Ministry of Agri-culture’s policy of a larger and larger corn acreage,particularly in areas unsuited to corn production.Stapledon and Davies claim that the temporary ley (leaor sown pasture) will yield more animal food than thebest permanent grass or any cereal, and will on the lowestestimate be equal to that of roots or kale. Even whenthese yields are transcribed into units of human-food thetemporary ley still compares favourably with most arable ’crops. Ley farming renders milk and corn productioncomplementary, and it would cheapen milk productionand make it less dependent on imported food-supplies.Some of the claims made for it may be’ disputed, butthere can be no doubt that the policy of " taking theplough round the farm " is gaining in popularity.

If farmers have reasonable financial security and goodtechnical advice they will no doubt respond to the nutri-tional needs of the nation, but the difficulties of their- tasks and the inducement required should not be under-estimated. At a discussion on milk held by the Nutri-tion Society some time ago Mr. J. L. Davies defined thethree primary requirements of the milk industry as (1)a ten-year plan involving expenditure of 1:100 million oncapital equipment urgently needed ; (2) a large measureof control over the diseases of dairy cattle; and (3)an adequate supply of good labour for which a six-dayweek would The necessary. The risks from disease are

greater in dairy-farming than in any other branch oflivestock farming, and the control of tuberculosis andbrucellosis, or even the production of clean milk, requiresa degree of supervision unnecessary in other branches.Before the war milk production accounted for over aquarter of the total agricultural output, and milk wastwice as important as any other single commodity ; butif arable farming and livestock feeding are profitable overan extended period it is possible that fewer and fewerfarmers will be interested in milk ; as one of them saidbefore the war, " If corn and beef production ever payagain I will gladly go into my dairy and smash everybottle in the place." The same applies to the men whomilk the cows, either by machine or hand ; there are

1. Stapledon, Sir G. and Davies, W. Ley Farming. PenguinSpecial, No. 99, 1942.