§ 1] MODIFICATION OF VITAL ACTIONS 15 



0.1%. Nbal and I have found that Stentor ccEruleus is killed 

 by a 0.001% solution HgClj in a few seconds. (Cf. p. 30.) 

 Ascarids die in a 0.1% solution in an hour. (Schrodee, '85.) 



Silver salts occasionally act upon bacteria more energetically 

 that those of Hg. Cadmium and zinc salts are poisonous — the 

 former more so than tbe latter. Thus, whereas 0.015% of cad- 

 mium sulphate inhibits reproduction of lactic acid bacteria, 

 0.1% of zinc sulphate is not injurious. Many salts of thallium 

 are likewise active. Thus Loew ('93, p. 37) found that in 

 0.1% thallium sulphate Spirogyra died in 4 to 6 hours. 



7. Substitution Poisons. — In this group Loew places cer- 

 tain nitrogenous substances which attack the amido and alde- 

 hyde groups of living protoplasm. These are extremely unstable 

 substances and may therefore be transformed by agents which 

 have no effect upon dead protoplasm. The supposed method 

 of action of a poison upon an aldehyde may be illustrated in 

 the case of the poison hydroxylamine (H2lSr — OH); which 

 justifies at the same time the term "substitution poisons." 



.0 .N-OH 



-R-Cf +H2=N-0H = E-Cf -I- HA 



\h \H 



any aldehyde. hydroxylamine. an aldoxim. 



Hydroxylamine. — This is a general and powerful poison. 

 Thus, among the lower organisms, a solution of neutral hy- 

 droxylamine of — 



0.001% kills diatoms within 24 hours. (Loew, '85°, p. 623.) 



0.005% kills in 36 hours Infusoria which withstand a similar con- 

 centration of strychnine. (Loew.) 



0.01% kills diatoms in something less than 15 hours; Planariaand 

 leeches in 12 to 16 hours. (Loew.) 



0.1% paralyzes the muscles of Eotifera in 10 to 15 minutes ; those 

 of Nais in 20 to 30 minutes. (Hofbk, '90, pp. 324, 325.) 



0.2% kills Rotifers, Copepoda, and Isopods in 1 hour (Loew) ; 

 stupefies Vorticella in from 2 to 10 minutes. (Hopee, 

 '90, p. 325.) 



0.25% stupefies Stentor in 10 to 20 minutes. (Hofeb.) 



Bemenylamidoxim and acetoxim, more complex derivatives of 

 hydroxylamine, are somewhat less poisonous. 



