Page:The Annual Register 1899.djvu/536

 112 SCIENCE. [1899.

quite as simple as this account would indicate. It appears that the body of the infected mosquito contains also black spores which retain their life in water for months, and withstand irrigation with liquor potassse. It is thought that these are "resting spores," and that, if swallowed in drinking water, they may originate fever. Besides Professor Koch has ascertained that a much commoner mosquito, Culex pipiens, which breeds anywhere, in wells and cisterns, is capable of conveying malaria. He considers, however, that the infective link is kept up through the cold months by the occurrence of "relapsing cases n of the disease, and could be broken by their proper treatment with quinine. Dr. Monaco finds that small quantities of bisulphate of quinine provoke the malarial parasite to quit the blood corpuscles, and that it is paralysed by a body dose of not less than half a gram.

In certain rare cancers Professor Plimmer finds enormous numbers of parasitic protozoa, which he has isolated and cultivated, and has introduced into animals with the production of tumours followed by death.

M. Chevalier claims to have isolated a parasitic fungus which he obtained from cancerous growths and from the blood of patients. The organism exists, according to the stage of its development, in the form, of conidia, mycelium, and sperules. It is highly resistant, surviving for ten minutes a temperature of 100° C. ; and its specific character has been confirmed by inoculations.

Herr Emmerich is leading the way to a production of antitoxins from bacillary cultures. By so doing he avoids the necessity of obtaining immunising serum from living animals. An enzyme extracted from a culture of Bacillus pyocyaneus is found to be antidotal to virulent anthrax, and in a less degree to typhoid, diphtheria and plague ; and its action is maximal in anaerobic conditions.

The ratio of adolescence to longevity was given by Buffon as 1/7, and has been stated by M. Flourens as 1/5. Dr. Hollis shows that in the shortest lived animals this ratio is less than in the longest. Thus, in the mouse which reaches maturity in three months and lives four years, the value is 1/15, in the Arab horse it is 1/4, and in man it is 1/2.

If the " germ-plasma " were persistent in the full Weismannian sense, there should be no variation in parthenogenetic offspring ; and acquired characters would not be inherited. Dr. Warren, after a mensural study of Daphnia maintains that there is, in the asexual progeny, a very con- siderable variability. The coefficient of correlation between mother and offspring he found to be -466. Comparing this with what obtains in the higher vertebrates, the coefficient of heredity between " brothers w being -4, he remarks that in the matter of inheritance a parthenogenetic mother acts as a " mid-parent." Further, Professor Errera claims that experiments made on Aspergillus niger prove that an acquired adapta- tion to the medium in which the organism grows is transmitted by inheritance.

Whether the chromatin in the nucleus of reproductive cells is the seat of heredity, as some imagine, remains to be demonstrated. Pro- fessor Sidgwick has been careful to point out that altered conditions cannot operate on the succeeding generation unless the reproductive