33 Mr. H. J. Carter on Amoeba princeps 



a pellicle over the surface of A. princeps, however thin ; and 

 the fact that very frequently, on the application of iodine, the 

 margin becomes of a deep violet colour^ while all the other parts 

 of this Rhizopod exhibit nothing but a more or less deep amber 

 tint, seems to confirm it by chemical differentiation. 



Such a covering has been demonstrated by Auerbach in A. 

 bilimbosa^, and more satisfactorily, on account, probably, of the 

 pellicula in this species being more rigid ; but Auerbach does 

 not show that it is coloured by iodine, although he figures 

 starch-globules thus turned blue within it. Some years since, 

 too, I pointed out the presence of starch, in all forms, through- 

 out Spongilla, which is but a congeries of amoebiform cells. 

 I have also shown that it exists in the chambers of the Forami- 

 fera ; so that starch may be set down as a common product of 

 the Hhizopoda. 



Returning to the pellicula, we must also infer that it is pos- 

 sessed of great elasticity and tenacity, so that it can yield a 

 covering to the pseudopodia almost to any extent (as proved by 

 the actinophorous rays of those Rhizopods which infest the cells 

 of plants remaining after the sarcode has withdrawn itself into 

 an interior or secondary cell) ; also that it admits of rupture (as 

 in the introduction of food into the sarcode), and yet can heal 

 over rapidly again. Thus it can undergo comparatively un- 

 limited extension even to discontinuity, but possesses no adhe- 

 siveness externally, as evidenced by nothing adhering to it 

 which is not seized and kept there by the instinct of the 

 animal. 



Furthermore, in A. princeps the pellicula is allied to the 

 cell-wall of plants by position, and, from chemical evidence 

 [i. e. when treated with iodine), by an amylaceous composi- 

 tion. 



Diaphane or Ectosarc. — This layer, as in other Amoeba, lies 

 immediately underneath the pellicula, and is distinguished from 

 the sarcode or endosarc within by its greater degree of trans- 

 parency and peculiar functions ; for while the sai'code is clouded 

 and presents a rotatory motion, the diaphane is clear and dis- 

 tinctly endowed with a locomotive and prehensile power. 



Analogy and actual observation w'ould lead us to infer that, 

 in certain if not in all instances, the ectosarc has the power of 

 passing through the pellicula by rupture of the latter — a fact 

 which becomes most evident when the pellicula is thick and re- 

 sistant, as in Amoeba bilimbosa, where it has been demonstrated 

 by Auerbach, especially in his third figure of this speciesf- 



* Siebold und KoUiker's Zeitschr. vol. vii. p. 365, pi. 19. figs. 1-5. 

 (Dec. 1855). 



t Loc. et tab. cit. 



