132 REVIEW — TROPICAL MEDICINE, ETC. 



Milk— destroyed, but, seeing that these do not occur in lmin;in milk, this was generally considered 



continued of no importance. The catalase was destroyed. On the other hand, oxydases nearly 

 always accompany catalase, so that by the final addition of a little catalase both these 

 classes of enzymes were restored to the milk. The nutritive qualities were unaltered, 

 and numerous cases had been recorded by medical men in which people (both infants and 

 grown-up people) had been doing very badly on raw or cooked (Pasteurised and sterilised) 

 milk, whereas milk thus treated had agreed very well with them. The taste and flavour 

 of the milk were practically unaltered. Non-sporing organisms and the vegetative forms of 

 sporogene bacilli are killed by the process. Regarding the spores there is some difference 

 of opinion, but in its latest improved foim it would seem that spores can be killed 

 with certainty. It would seem also that the process renders the milk more digestible. 



There are many other valuable papers, but the above are the most recent in the list, 

 and, possibly, the most useful to the reader in the Tropics. One may conclude by noting 

 an account" of the " Victoria " brand of homogeneous fresh milk, said to be of special 

 value in the Tropics. It is a fluid, not a condensed milk, and is guaranteed free from 

 preservatives, chemicals, sugar, or any added matter whatsoever. It is a pure milk without 

 additions, and in such a state that it can be used at once as it is poured from the tin. 

 The slight flavour induced by it in the process of preparation is said to be pleasant and 

 by some is regarded as an improvement. I have seen and tasted a sample of this milk after 

 it had been one year in the Sudan, and certainly it left nothing to be desired so far as 

 appearance and flavour go. 



Mosquitoes. Only a few more or less general papers will be here considered, as 

 these insects, so far as the Sudan is concerned, form the subject of a special paper by 

 Mr. Theobald. {See Third Report) 



The longevity of mosquitoes has been the subject of enquiry, especially as regards 

 Stegnmijiafasriatti, or rather (Jalopiis, as the carrier of yellow fever has been re-named. Finlay -* 

 of Cuba, iias found that when an infected Steriomi/in is not allowed to bite and get its 

 due nourishment of warm blood, it is prevented from laying its normal complement of 

 eggs, and may live as long as four or five months. This is important in connection with 

 the outbreak of yellow fever. 



A very important and practical report is that by Smith, ^ of New Jersey. A great deal 

 of information is given regarding the habits of mosquitoes, both iinaijiiies and larvee. The 

 latter are stated to have apparently little or no influence in purifying the waters they 

 inhabit. Their food consists chiefly of the spores of algoe and other vegetable matter. 

 One interesting point discussed is as to whether blood is a necessary food to enable a 

 female mosquito to mature her eggs. " As to this," says Smith, " there is still considerable 

 doubt," and continues : — 



It is certainly proved withiu my own experience that Culex inpicns may oviposit without food other than 

 that which could be found under the net covering a common wooden pail in which the parent developed. It 

 is certain, too, th.at there are long stretches of salt marsh breeding areas on the New Jersey Coast, where 

 mosquitoes occur by the million, where the foot of man does not touch once a year, where no warm-blooded 

 things save a few 'birds abide, and where blood is absolutely unattainable. Of course, a large percentage of 

 these salt marsh breeders migrates inland and feeds bountifully ; but none of these migrants seem to be fertile 

 and the blood food produces no developing ovaries. On the other hand, the vast majority of specimens in 

 which ovaries are found to be well developed showed traces of blood food in the stomach. This statement should 

 be qualified, however, so as to apply to C. sollicilans only; in 0. caidalor there is usually no trace of food 

 observable to the naked eye when ovaries are fully developed. 



Very few direct experiments were made on this point with other than the species above mentioned ; but 

 published records indicate that in captivity some species will not develop eggs or lay them until after a meal 

 of blood. Whether that would hold equally true of the same species, under entirely natural conditions, may be 

 considered questionable. Incidentally it may be said that not only are all warm-blooded animals and all birds 

 attacked by mosquitoes, but the reptiles also, where they afford an opening. On the whole, the balance of 

 evidence is perhaps against the idea that blood is a necessity for egg development. This is further indicated 

 by the fact that ^/op/icte goes into hibernation without having fed, and that there are few records of biting 

 early in the scison, before these hiberniitiug forms lay their eggs to produce the first brood of larva;. 



"That mosquitoes feed upon vegetable juices as well as blood is certain. As to the males, it must be so, if 

 they feed .at all ; for their mouth structures are not adapted to puncture the skin or to suck blood. Females 

 have been observed along with uectar-sucking males, but seemingly these abandoned the vegetable food readily 

 when the animal odour advised them of something more to their taste." 



• Journal of Tropical Mcdiciiie and Hygiene, 2nd March, 1908, Vol. XI. 

 " Finlay, C. Quoted in British Medical Journal, September 14th, 1907. 



= Smith, J. B. (1904), " Report of the New .lersey State Agricultural Exp. Station on Jlosquitoes." 



• Article not consulted in tlic original. 



