the Distinctive Characters in Amoeba. 131 



laceration, not necessarily by the folding together and union of 

 the torn margins, but by the immediate development of ectosarc 

 upon the torn surface ? Let the process be called instantaneous 

 cicatrization, or what else we will, the phenomenon remains the 

 same. 



Again, let me ask what prevents the food-vacuole * from 

 collapsing suddenly when relieved of its contents by absorptive 

 digestion, as often happens ? Admitting that the watery con- 

 tents prevent collapse from taking place, why do not all the 

 vacuoles, when crowded together, as they frequently are, coalesce, 

 instead of remaining for the most part- distinct from one an- 

 other ? t And lastly, why do the globules of sarcode, when ex- 

 truded under pressure by rupture of some part of the surface, 

 and floating side by side (as described and figured by me in the 

 'Annals' for May, p. 370, pi. 9. fig. 8), show no tendency to 

 coalesce, unless it be that the inner layer in the former case, 

 and the outer layer in the latter, by which each globule is sur- 

 rounded, instantaneously becomes converted into ectosarc by 

 simple contact with the surrounding medium ? 



Chemical reagents, when applied to a mass of sarcode, prove 

 nothing beyond their efi"ects on that substance ; that is to say, 

 they do not demonstrate the primary presence of a membranous 

 layer, even where they succeed in producing the semblance of 

 one. And this is the case without reference to the well-established 

 fact that certain chemical substances frequently render more 

 distinct structures which are already imperfectly visible or de- 

 monstrable without their employment. 



It is obvious that when a food -particle is incepted by an 

 Amoeba, the vacuolar cavity receiving it must either be formed 

 of ectosarc or endosarc, or of both combined. If it be urged 

 that it is composed of the former, it follows that, at every incepr 

 tion of food, so much ectosarc as is requisite to surround the 

 object must be abstracted from the general surface of the body. 

 Hence, when the quantity of ingesta is large, as frequently 

 happens, the greater part, if not the whole, of the ectosarc 

 must speedily be conveyed into the interior, leaving the viscid 



* See my paper in the 'Annals ' for June, p. 436. 



t It will be recollected that I have endeavoured to prove, by the 

 mode in which foreign bodies are incepted as food, that the food-vacuole 

 is formed either of an intussuscepted portion of the ectosarc around 

 the point of inception, or, supposing the food-particle to be forced 

 through the ectosarc by the rupture of the latter, that the simultaneous 

 admission of a portion of water at once converts the endosarc, of which 

 the boundary of the cavity is formed, into ectosai'C. It is by this means 

 that the entire food-vacuole is sometimes extruded through an orifice in 

 the villous region — a thing which could not take place were the food- 

 vacuole formed of endosarc. 



9* 



