150 BULLETIN OF THE 



projected far up among the contractile fibrillae. Tailed nuclei have 

 been found by various observers, and sometimes the form has been 

 attributed to mechanical injury in cutting. But this cannot be the case 

 here, since they were plainest in sections 20 fx thick at a level distinctly 

 between the two surfaces of the section. From the general appearance 

 of the sections I doubt the probability of the form being due to pres- 

 sure in killing or preparing, and am inclined to regard their form as 

 normal. Such nuclei have been explained as nervous; the only argu- 

 ment which can be said to favor that view in this case is their position, 

 and the absence of other known nervous terminations in the muscular 

 layer. 



The striated zone is narrow in the anterior chamber and at the pos- 

 terior end of the body, but is elsewhere of nearly uniform width in any 

 one specimen. It remains entirely colorless in carmine stains, but takes 

 up ha3matoxylin with avidity and does not give it up in acid fluids. 



The protoplasmic portion of the muscular cell is highly granular and 

 ordinarily does not stain at all. In the protoplasmic zone, however, there 

 are cells which stain in eosin much deeper than the remaining elements 

 (Fig. 29, x). The contents of these cells are so finely granular as to 

 appear almost homogeneous. Lying in the body cavity near these cells 

 are corpuscles, which in general appearance and affinity for stain are 

 identical with them. It will appear probable, I think, from the figures 

 given (Figs. 28-30), that these corpuscles are derived by abstriction 

 from the deeply staining cells of the protoplasmic zone. They are 

 found of all sizes, but never in very great numbers. There is some evi- 

 dence to show that the deeply staining cells are the proximal ends 

 of certain muscle cells, the contents of which are perhaps chemically 

 altered ; the corpuscles, however, never contain nuclei, so far as I have 

 seen. In view of the evident correlation between the thickness of 

 the muscular wall of the body and the sexual maturity of the ani- 

 mal, it is possible that the function of these corpuscles is nutritive. 

 This will be discussed in connection with the description of the sexual 

 organs. 



Evidence which goes to prove the formation of true cells from this 

 layer is obtained from the study of the female in which the eggs were in the 

 most immature condition of any which I had. Here (Plate IV. Fig. 59) 

 sections show the body wall to be composed of the layers already de- 

 scribed, except that the protoplasmic portion of the muscle cells is 

 much shorter, and there seem to be proportionally fewer nuclei and 

 fewer cells than in the sections previously described. In addition 



