BLACKMAN : THE SPERMATOGENESIS OF SCOLOPEXDRA. 19 



bodies are united together into a riug-like hand, as descrihed by Mc< iregor 

 ('99) for Amphiuma ; hut during this earlier stage the ring is composed 

 of a number of separate bodies in close apposition to each other. The 

 central portion of the spindle remnants extending through the opening 

 in each of the two cells is still plainly of a fibrous character, although 

 the component parts are often somewhat masked by the reticula- 

 tions of the less modified archoplasm surrounding it. The remnants of 

 the spindle proper fuse indistinguishably with the mantle of archoplasm 

 surrounding the nucleus. This, as I have already said, is of a reticular 

 structure similar to the cytoplasm, of which it is indeed only a slightly 

 modified form. It differs from this, however, in being more dense, — i. e. 

 the network encloses finer meshes — and in containing at certain regions 

 depositions of fine granules. These thickenings are generally toward the 

 periphery of the archoplasmic zone, and are often so pronounced as 

 to suggest the presence of a definite membrane. In other cells, however, 

 this outer layer is broken up into a number of irregular portions, which 

 plainly consist of a network in the meshes of which are enclosed numerous 

 granules. When examined under low powers, these bodies seem to be 

 homogeneous or of a very finely granular structure, but with higher 

 magnification the true structure is evident. In the inner zone the 

 reticular character of the archoplasm is much more evident, as here 

 the structure is not so obscured by the deposition of granules. This 

 region is but little more dense than the undifferentiated cytoplasm or 

 the network within the nuclear vesicle. 



In the outer dense area of archoplasm there is always an irregular 

 ovoid or globular body containing two small darkly stained bodies 

 (Figs. 1G, 133). This body, which is the " Idiozome " of Meves, or 

 attraction-sphere, is not identical in structure with the adjacent archo- 

 plasm, but is denser, and exhibits no reticulations even with the highest 

 magnification available. In this idiozome there is no differentiation into 

 zones, as has often been described for other objects, but it appears to be 

 a simple granular mass containing two denser bodies. This mass prob- 

 ably represents that part of the archoplasm which is derived from the 

 mantle fibres and astral rays, and in the telophase of the spermatogonium 

 surrounds the centrosomes during their migration around the mass of 

 chromosomes (Figs. 7 and 9). The identity of the idiozome with this 

 body is plainly shown in Figures 7-16. 



Besides the centrosomes there is generally a rather large number of 

 coarse granules distributed throughout the archoplasm and the undif- 

 ferentiated cytoplasm at various points. These, however, differ from the 



