ZOOLOGY AND BOTANY, MICROSCOPY, ET 543 



Pathogenic and Teratogenic Agents.* — E. Eabaud seeks to give 

 precision to this contrast. A teratogenic agent induces modifications 

 such that the living matter loses none of its essential qualities ; tbere is 

 a novel distribution of histological differentiations, and there is load 

 variation in the rapidity of growth. A pathogenic agent induces de- 

 structive processes ; there is at leaat a tendency to total or partial 

 destruction of certain protoplasmic elements, or to their transformation 

 into inert substances. The vital processes are hindered or bereft of 

 their completeness. 



Growth and Auto-Intoxication, f — F. Houssay has plotted out the 

 progressive changes in the weights of a brood of chickens, and com- 

 pared the curves with those of Deschamps expressing the growth of 

 Protozoa limited by inanition or auto-intoxication. As inanition could 

 hardly be supposed in the conditions observe 1, Houssay thinks that it 

 is auto-intoxication which restricts the rate of growth. He maintains 

 that auto-intoxication is a constantly present check on the growth of 

 Metazoa. 



Biological Test for Blood. — G. H. F. Xuttall has described the 

 preparation of so-called specihc anti-sera. i To obtain an anti-serum 

 for human blood, the blood is injected intraperitoneally into rabbits. 

 After about five injections, given at intervals of three or more days, the 

 rabbit is bled to death, and its blood-serum is collected. This serum 

 has acquired the remarkable property of producing a precipitation im- 

 mediately on its being added in small quantity to human blood-serum. 



Xuttall has discovered the interesting fact § that the anti-seium 

 above described has no effect upon the blood of other mammals and 

 other vertebrates (230 different kinds), with the single exception of 

 monkey bloods. Similarly, if labbits are treated with the blood of the 

 horse, dog, ox, sheep, &c, anti-sera are formed which produce precipita- 

 tions only in the bloods of the animals whose blcod was used for 

 treatment, or, to a less extent, in the bloods of nearly allied animals. 



Thus the blood-test comes to be a physiological criterion of relation- 

 ship. The new world monkeys give a less marked reaction with the 

 anti-serum for human blood than do the old world monkeys ; and the 

 test gave a negative result when applied to the blood of two species of 

 Ltiiutr. 



In a subsequent paper || Xuttall notes that anti-dog serum yielded 

 positive results only with bloods of other Canidae ; anti-horse serum only 

 produced a reaction with the blood of horse and donkey ; the bloods of 

 Tragulidfe and Camelidse gave no indication of relationship with the 

 true ruminants, and so on. 



Anti-pig serum pr< duced marked clouding (remote relationship?) in 

 A number of mammalian bloods, but only once a (very slight) clouding 

 in a non-mammalian blood (experimental error?). 



* Couiptes Rendus. csxxiv. (1902) pp. 915-7. 

 t Tom. cat, pp. 1233-5 (1 fig.). 



% Brit. Med. JourD., 11th May, 1901, p. 1141; 14th September. 1901, p. 669 ; 

 Journ. of Hvgitne. 1st July. 1901, pp. 367- 87. 



§ Proc. Boy. S< c. London, lxis. (1901) pp. 150-3. 

 | Proc. Cambridge Phil. Soc., xi. (1902) pp. 334-6. 



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