the Distinctive Characters in Amoeba. 147 



not, I am unable to decide." And it would appear that a similar 

 opinion was held by him in 1856, from the subjoined statement 

 extracted from the 'Annals/ vol. xvii. p. 358. "In Amoeba, 

 sometimes, the sarcode appears to be filled with such vesicles *, 

 which not only now and then burst into the large one or vesicula, 

 but, when the latter has discharged itself, frequently burst of 

 themselves externally.'^ 



Without dwelling on the perplexing modifications of opinion, 

 regarding the number of the contractile vesicles in Amoeba and 

 Actinophrys, which are embodied in the above extracts, I may 

 observe that I regard the origin of the abnormal vacuolation as 

 totally distinct from that of the multiple or supplementary con- 

 tractile vesicles ; and, bearing in mind that in Amoeba it is con- 

 nected with an exhausted condition of the organism, it appears 

 explicable on the supposition that the effete watery particles, 

 being unable to obtain a discharge through the ordinary endos- 

 motic transference to the true excretory organ (namely the 

 contractile vesicle, which now acts very sluggishly), are poured 

 out, and produce vacuoles at any portion of the endosarc where 

 a rudiment exists (see ante, p. 146). Should this view be 

 correct, it would appear that the endogenously formed vacuoles 

 constitute a rudimentary water-respiratory system f ; whilst the 

 contractile vesicle serves to throw ofi" such portions of the watery 

 particles as are effete ; and the food-vacuoles (which are invari- 

 ably formed at the surface) ipso facto constitute digestive cavi- 

 ties, whose assimilative function is called into action by the sti- 

 mulus of organic objects capable of solution by them. In this 

 sense I fully acquiesce in Mr. Carter's opinion that a digestive 

 power is essentially inherent in sarcode generally, although I can 

 no more admit the conversion of ectosarc and endosarc to be the 

 result of a digestive process, as urged by him (' Annals,' July, 

 p. 37), than that the absorption of a morbid growth, or the con- 

 stant decay and renewal of parts, in the case of the higher animals 

 is similarly brought about. 



The conversion of endosarc into ectosarc I regard as analogous 

 in its character, if not identical, with coagulation, the effect 

 being produced by the mere contact of sarcode with the medium 

 in which it resides ; whilst the converse process constitutes an 

 inherent vital function of the animal protoplasm. Should this 

 view be admissible, we have presented to us a phenomenon bear- 

 ing, in the most important manner, on the general question of 

 development, and one which, I venture to affirm, is far more 



* The context shows that the supplementary contractile vesicles are here 

 referred to. 



t The Diatomaceae and Desmidiaceae, when becoming languid and un- 

 healthy, present this inordinate vacuolation. 



10* 



