1920] VETERINARY MEDICINE. 275 



periments of his own, the evidences of bacterial variation in relation to their 

 bearing,' on the possibility of transmutation of species among bacteria, and ad- 

 vances a hypothesis as to the nature of disease. This hypothesis assumes that 

 each separate symptom of disease may be attributable to a separate and dis- 

 tinct bacterial enzyui', these bacterial enzyms being ultramicroscopic parasites 

 of the bacteria capable of being dissociated from the organism to which a par- 

 ticular disease is attributed and becoming attached to another organism, thus 

 producing the effect of transmutation. 



Studies on pathogenic anaerobes. — I, Biology of Bacillus Avelchii, B. 

 Jablons {.Jour. Lab. and Clin. Med., 5 (1020), No. 6, pp. S7//-385, fi<js. 2).— The 

 Biorphologj") cultural characteristics, biochemical properties, serologic char- 

 acteristics, and pathogenic power of B. welchii are described with many 

 references to tlie literature ou the subject. 



The differentiation of the paratyphoid enteritidis group. — \^I, Irregular 

 and variable strains, E. O. Jordan {Jour. Infect. Diseases, 26 (1920), No. 5, pp. 

 Ji27-.'f3.i). — This is in continuation of the series previously noted (E. S. R., 41, 

 p. 5S0). 



Bacillus enteritidis infection in laboratory rats, P. R. Cannon (Jour. 

 Infect. Diseases, 26 (1920), No. 5, pp. /f02-40-'f).—" In an epidemic among white 

 laboratory rats, extending over a period of four weeks, 4.5 of 52 died. An or- 

 ganism which is culturally and serologically identical with B. enteritidis was 

 isolated from the heart blood of 31 of 35 rats examined. This organism, when 

 Injected intraperitoneally or subcutaneously into other rats, or when fed, 

 caused the death of the rats, and the organism was recovered from the heart 

 blood and spleen." 



Observations on the life history of Ascaris lumbricoides, B. H. Ransom 

 and W. D. Foster (17. S. Dept. Agr. Bui. 817 (1920), pp. J,7, figs. 6).— In this 

 bulletin the authors review the present status of knowledge of the biology of 

 A. lumbricoides, including data presented in papers previously noted (E. S. R., 

 43, p. 80), and present the results of further investigations, including tlie de- 

 tails of 23 feeding experiments conducted. The autliors find the correspond- 

 ing parasite of the pig (A. suum Goeze or A. suilla Dujaridn) to be morphologi- 

 cally indistinguishable, and they probably are specifically identical. A 3-page 

 bibliography is included. A general summary given by them is as follows : 



"The embryos in the eggs of A. suum or A. lumbricoides in the presence of 

 oxygen and moisture may reach full development in 10 days if incubated at 

 a temperature of about 33° C. (91.4° P.), development proceeding more slowly 

 at lower temperatures and being inhibited by the lack of oxygen or moisture. 

 The shell of the egg is insoluble in many chemical reagents. Within the shell 

 there is a thin membrane which is highly impermeable, and even more re- 

 sistant to solution than the shell itself. The shell may be dissolved with anti- 

 formin, leaving the embryo inclosed in the membrane, in which condition the 

 embryo may continue active for several days. 



" Hatching of the ejubryo may occur accidentally outside of the body of a 

 host, but occurs normally only in the small intestine. Hatching also occurs 

 if the egg is introduced beneath the skin. The factors that govern the hatch- 

 ing (»f A.scaris eggs are yet to be determined. Martin's conclusions that hatch- 

 ing is caused by alkaline, or even neutral solutions, acting at body tempera- 

 ture have not been confirmed. Ascaris eggs in large numbers may be con- 

 veniently obtained and developed to the infectious stage for experimental use by 

 removing the eggs from the uteri of female worms and incubating them In a so- 

 lution of formalin placed in shallow dishes and stirred every few days to 

 Insure sufficient aeration. 



