38 THOS. H. MONTGOMERY jr., 



essential characteristic is found in the mode of arrangement of the 

 chromatin and of the idiozome substance. The chromatin, while still 

 showing evidence of the continuation of the elongate chromosomes 

 characteristic for the preceding telophase, is now marked by rami- 

 fication and anastomosis of the chromosomes , i. e. the chromatin 

 assumes a more or less reticulate arrangement, forming a more or 

 less continuous, irregular network, in which individual chromosomes 

 can no longer be distinguished. The heavily-monilated arrangement 

 of the telophase has given place to a connected network of narrower 

 strands of chromatin. The latter are irregular in diameter and form, 

 and connected together and with the nuclear membrane by numerous, 

 delicate linin threads. The ramifications of the chromatin threads 

 are more clearly seen in the cells of the large generation (Figs. 99, 

 100) than in those of the small (Figs. 95-98), since in the former 

 the nucleus is larger and more clear, on account of the chromatin 

 strands being more slender and more separated from one another. 



The chromatin nucleolus (w. 2, Figs. 95—100) lies now in contact 

 with the nuclear membrane, and is rounded with the exception of that 

 side flattened against the nuclear membrane. It has undergone a 

 morphological change, since it now contains a central lighter globule, 

 which does not appear to be connected with the exterior by any duct. 

 Since the volume of the chromatin nucleolus is larger at this than at 

 preceding stages, and since this increase in size is probably owing to 

 the presence of the globule within it, it would seem probable that 

 the substance of the latter is derived from without, more particularly, 

 judging from the peripheral position of the chromatin nucleolus, 

 derived through the nuclear membrane from the cytoplasm, a mode 

 of growth which is frequent in true nucleoli (cf. my previous observations, 

 '98). A less probable explanation would be that the globule is a chem- 

 ically changed portion of its substance. The chromatin nucleolus is now 

 larger in cells of the large than in those of the small generation ; though 

 in the early anaphase of the spermatocytes it has the same size in both. 



The true nucleolus (w, Figs. 95 — 100) attains its maximum 

 dimensions at the rest stage, is nearly homogeneous in appearance, 

 and without a limiting membrane; its chemical consistency appears 

 to be the same as before. It occupies a position within the nuclear 

 cavity, never in contact with the nuclear membrane. In a few cases 

 it was in contact with the surface of the chromatin nuceolus: this 

 position, characteristic for it in the spermatocytes of Harpcdus, must, 

 from its rarity in Pentafoma, be considered accidental in the latter 



