702 GEOFFREY LAPAGE 



stain more feebly than the others on the same sHdes, the 

 nucleus often not staining at all. These may have been 

 spheres which were undergoing digestion, or they may have 

 been merely dead ones. In the majority of cases the spheres 

 certainly seemed to resist digestion, although it was evident 

 that most of them were killed by their sojourn in the food 

 vacuole or were, at any rate, so much damaged that they were 

 unable to resume their activity after they were extruded. The 

 appearance of a contractile vacuole in them indicated an attempt 

 at the resumption of vitality ; but usually the attempt went 

 no further and the extruded spheres disintegrated if they were 

 not again ingested. In a few cases abortive attempts at amoe- 

 boid movements occurred ; and in fewer still these were success- 

 ful and the sphere became transformed again into a small 

 amoeba which was apparently little the worse for its experi- 

 ence. 



It is evident, therefore, that the amoebae found difficulty, 

 at least, in digesting other amoebae which they took up. 

 They might, therefore, extrude them again, just as they will 

 extrude other indigestible material. If these extruded amoebae 

 had been killed by their sojourn in the food vacuole or died soon 

 after extrusion they might be again ingested by other amoebae ; 

 and it is probable, although I can produce no evidence to prove 

 it, that these dead or dying amoebae could be digested. One 

 is reminded here of the fact that, in Vertebrates, the gastric 

 juice does not digest the mucous membrane of the stomach, 

 unless that is damaged or in a pathological condition, but that 

 post-mortem digestion of the stomach can and does occur. 



Another reason for the extrusion of the spheres is suggested 

 by the observation of Ehumbler, as quoted by Minchin (19 o), 

 that amoebae disgorge any food matter that they may contain 

 under the influence of strong light, such as that to which they 

 are subjected when they are brought into the field of the 

 microscope. That this is not the only reason in this case is 

 shown by the frequent occurrence of free spheres in the cultures 

 themselves, before any of the fluid had been examined under 

 the microscope. They could be picked up from the bottom 



