THE "INOTAGMAS" 275 



theory does not justify the expectations of its founder, and 

 I will attempt to explain this rather more fully. 



Engelmann wishes to refer the spherical form assumed 

 by naked protoplasmic bodies, consequent upon stimulation, 

 to the fact that all the inotagmas become spherical at the 

 same time, that is to say, become contracted, as a result of 

 which " the surface attraction which they exert upon one 

 another, that is to say, the cohesion of the entire mass, must 

 become sensibly equal everywhere and in all directions." 

 He thus introduces a new assumption, namely, that the 

 mutual attraction of the inotagmas in the resting condition 

 is different in different directions, corresponding to their 

 elongated form, without, however, paying closer attention 

 to this subordinate assumption. Now even if, as postulated 

 by the above explanation of Engelmann, the mutual attrac- 

 tion of the inotagmas becomes equal everywhere and in all 

 directions, there will, in my opinion, only result a tendency 

 towards the spherical form if the protoplasm at the same 

 time obeys the general laws of fluid bodies ; and the cause 

 of this tendency to a spherical form can only be, as Engel- 

 mann himself also formerly assumed, the surface tension, 

 which, with equal cohesion throughout, only attains to 

 equilibrium under this condition. 



If the mass be not fluid, it seems self-evident that the 

 rounding off of the inotagmas and the equality of their 

 cohesion cannot produce a tendency to a spherical form, 

 but at most slight alterations of form. If, on the other hand, 

 the mass is fluid, the same point really holds good, only 

 then, as soon as the cohesion becomes equal on all sides, 

 the surface pressure necessarily produces the spherical form. 

 If we imagine to ourselves an irregularly -shaped Amoeba, 

 or even the richly-branched pseudopodial network of 

 many Sarkodina and Myxomycetes, it is, in my opinion, 

 quite inconceivable how these structures should contract 

 into a spherical form merely as the result of the inotagmas 

 becoming rounded off, and of their mutual attraction being 

 equalised on all sides ; for these processes, as has been said, 

 could only produce certain alterations in form, since there is 

 no reason at all for the assumption of a spherical form as 



