96 rilOCEEDINGS OF THE ACADEMY OF [Jan., 



credit them to muscular action. They were movements evidently to 

 be compared with the peristalsis of the Polycystidea, which, as I have 

 pointed out, cannot be credited to endoplasmic currents. Moreover, 

 they were so rapid and so evidently powerfvil that a comparison with 

 what we see in Amoeha fails. Further, if they were caused by endo- 

 plasmic movements, the myocyte is left without a function, which is a 

 most improbable supposition. 



It therefore seems more probable that the polymorphism of the 

 Monocystidea is due to muscular action. Hence, by analogy, the poly- 

 morphism of the Polycystidea should be accounted for in the same 

 way. Nevertheless, as I have indicated, this view has certain objec- 

 tions and the decision is better postponed until additional data arc 

 obtained. 



In an article on the progression of gregarines (Crawley, 1902). I 

 endeavored to show that when the protomerite of a gregarine is bont 

 to one side or the other, the siu-face of the deutomerite shows a wave 

 which passes backward and transversely at the same time. My obser- 

 vations also indicated that the extent of the bending of the protomerite 

 conditioned the extent of this wave. Further, when the bending of the 

 protomerite was first to one side and then to the other, that is, when it 

 oscillated, the transverse component of the wave on the sm-face of the 

 deutomerite was also first to one side and then to the other. I there- 

 fore regard these two manifestations of activity as due to the same 

 contraction of the myocyte. That is, a contraction wnich causes the 

 protomerite to bend causes also this wave to pass over the surface of 

 the deutomerite. 



Certain criticisms which have been made upon this paper lead me to 

 suppose that I did not bring out this point as clearly as desirable. I 

 shall therefore make use of a comparison. If we bare the forearm and 

 then slowly close the fingers tightly, a muscular wave passes upward 

 and outward along the dorsal surface of the arm. By alternately con- 

 tracting and relaxing the fingers, this wave exhibits an alternate trans- 

 verse movement. In this case, the conspicuous result of muscular 

 contraction is the closing or opening of the hand, but it is necessarily 

 correlated with the disturbance on the surface of the forearm. In the 

 gregarine, the oscillation of the protomerite is the conspicuous mani- 

 festation of muscular activity, and, under ordinary conditions of obser- 

 vation, the only one which is seen. But it is always accompanied by 

 the wave on the surface of the deutomerite. The result is that a given 

 point on the gregarine's surface pushes backward and transversely 

 upon whatever may be in contact with it. This brings about a move- 



