22 CHEMICAL AGENTS AND PROTOPLASM [Cii. I 



producing a change in size of the nucleus. (LoE\v, '92.) A 

 1 % solution kills the nerves of a frog in 2 hours. 



9. Special Poisons. - - Toxic Protein Compounds. Little need 

 be said here concerning the recent discoveries of poisonous 

 albuminoids excreted by disease-producing bacteria, or of those 

 secreted by the parasitized body (alexines). Similar compounds, 

 highly poisonous to Vertebrates, have been extracted from the 

 seeds of some Phanerogams, e.g. ricin, from the seeds of Rici- 

 nus communis (castor-oil bean); abrin, from the seeds of the 

 leguminous Abrus precatorius, L. ; and phallin, from the toad- 

 stool Agaricus phalloides, Fr. Finally, in this group may be 

 placed a large number of protein substances derived from 

 animals, which are more or less poisonous to a greater or 

 smaller number of kinds of protoplasm. The poison of the 

 rattlesnake (Crotalus) and of the cobra (Naja) is fatal to 

 Vertebrates in small, hypodermically injected, doses. Hydra, 

 Turbellaria, Rotifera, and Crustacea are also affected by it ; 

 but Infusoria and Flagellata are apparently unaffected. (HEI- 



DENSCHILD, '86, p. 330.) 



It is important that, according to the experiments of several 

 investigators, among the earlier of whom may be mentioned 

 DAREMBERG ('91) and BUCHNER ('92), the various species of 

 Vertebrates possess protein substances in their blood serum 

 which are to a certain extent injurious to other species, since 

 the blood serum of any one species will destroy the red and 

 white blood corpuscles of another. The poisonous action of 

 these animal protein substances seems to be due to their un- 

 stable character, whereby they easily form unions with the 

 unstable groups of the protoplasm, frequently producing 

 thereby violent poisons which work as substitution poisons. 

 (LoEW, '93, pp. 81-84.) 



Alkaloids. These basic, nitrogenous compounds have, for 

 the most part, very complex molecules, so that their structure 

 has, in many cases, not been determined. Consequently the 

 nature of their chemical action upon protoplasm is, in general, 

 unknown. 



LOEW suggests ('93, p. 85) the following theory of action of 

 alkaloids. The bases unite with the active protein substances 

 of the cell, and thereby introduce a disturbance of equilibrium 



