c .5 JOHNSON. [Vol. VI 11. 



flow together into one ; and it seems highly probable that this 

 is the mode by which fsecal matter distributed in vacuoles 

 throughout the body is gradually collected into one large 

 excrement-vacuole. 



As to the process of defecation, Moxon ('69) says : " Not far 

 from the opening in the contractile vesicle in Stentor is the 

 point of surface which gives exit to the solid residues of the 

 creature's food. ... Its place is marked, not by any pore or 

 opening, but by an irregularity or break in the course of one or 

 two of the longitudinal blue bands before described. . . . The 

 mass to be thrown out is brought to the surface and simply 

 forced through it, sometimes carrying with it a thread of the 

 glairy contents of the saccular body of the animal." I have 

 observed no interruption in the course of the stripes at the 

 usual place of defecation, and cannot regard it as a characteristic 

 feature. The "break" in the stripes is rather to be looked 

 upon as the cicatrix resulting from a previous rupture of the 

 integument at that point. 



Concerning the extrusion of faecal matter, two things are to 

 be noticed : (i) the contractile power of the cytoplasm sur- 

 rounding the excreta, (2) the rupture and subsequent closure of 

 the pellicula and ectoplasm. The contraction of the endoplasm 

 around the excreta is comparable to the contraction of that 

 about the contents of the pulsating vacuole, but its action is 

 certainly slower and less vigorous. Yet it is sufficiently 

 perfect to eliminate every particle of excreta in the vesicle, but 

 usually, as Moxon states, with the loss of some of the cyto- 

 plasm. 



Inasmuch as defecation can occur with equal success at many 

 points it is evident that the contractile power of the cytoplasm 

 is diffused, not restricted to one place, as we should probably 

 think to be the case if we considered the contractile vacuole 



alone. 



The rupture of the integument is an interesting process. 

 There first appears over the excrement-vacuole a longitudinal 

 slit through pellicle and ectoplasm, exposing the excreta. The 

 lips of the slit rapidly spread apart, and in a moment lay bare 

 the whole exterior surface of the mass of excreta, even though 



