1] MODIFICATION OF VITAL ACTIONS 15 



0.1%. NEAL and I have found that Stentor cceruleus is killed 

 by a 0.001% solution HgCl 2 in a few seconds. (Cf. p. 30.) 

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



Silver salts occasionally act upon bacteria more energetically 

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

 former more so than the 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 (H 2 N--OH); which 

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



,0 ^ N 



R_C5 + H 2 =N-OH = R-Cf + H 2 0. 



\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. (Losw, '85 a , p. 523.) 

 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; Planaria and 



leeches in 12 to 16 hours. (LoEW.) 

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



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

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



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



'90, p. 325.) 

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



Benzenylamidoxim and acetoxim, more complex derivatives of 

 hydroxylamine, are somewhat less poisonous. 



