Sur l'action cytonarcotique des sels de nickel chez Paramecium caudatum Ehrb.

SYNOPSIS. Cytonarcotic action of Ni-chloride Ni-sulfate and Ni-nitrate is studied with mating types C and D French variety II of P. caudatum = XV and XVI American variety 8. The time which is necessary to make the ciliates motionless is proportional to Ni ion number in solution, but, in any case, there is a minimum time for narcosis. Mating types have very different sensitivity. C is more sensitive than D. Ba⁺⁺ and Ca⁺⁺ strongly antagonize the action of Ni⁺⁺. This antagonism, only biological, depends on the simultaneous presence of the ions in solution and has maximum value when the ions are in definite and constant proportion. Formation of digestive vacuoles involves reactions which make the ciliate resistant to Ni probably by decrease of membrane permeability. After narcosis, about twenty generations must pass before the rate of multiplication is again normal.