702 JOSEPH MANGAN. 
in parts double, layer of superficial cells, upon the dome 
shaped, or at times conical, manubrium of a completely 
formed medusa. 
The cells of this layer vary but little in size, and contain 
a proportionately large nucleus (fig. 1). The chromatin 
forms a close reticulum, and is mostly concentrated at the 
nodes. There is a single deeply staining chromatin- 
nucleolus. 
In the material containing the subsequent stages the ova 
were practically all approaching the end of their growth 
pericd, or in some later phase. The smallest of the two or 
three exceptional instances (fig. 2) apparently exhibited the 
oocyte as a plasmodium resulting from fusion of the cyto- 
plasm of several oogonia, the nucleus of the oocyte, however, 
alone persisting. Some oogonial cells (fig. 2) were in pro- 
cess of fusion with the ovum, and in others the nucleus was 
becoming indistinct. ‘The germinal vesicle had increased in 
size, its chromatin now forming open branching’ strands. 
The nucleolus was present. In the next smallest (fig. 5) the 
nucleus was larger, showing to better advantage the branch- 
ing chromatin strands; the single nucleolus persisted un- 
changed. 
In what I took to be the succeeding stage to the foregoing 
two cases the nucleolus was never present in the germinal 
vesicle; which latter body seemed to have reached its limit 
of expansion. The elongate chromatin strands (fig. 4) were 
fairly numerous, lying mostly in the peripheral portion of the 
nucleus, and often exhibiting a ragged outline. 
In the greater proportion of growing ova examined the 
chromatin strands were less conspicuous, fewer in number, and 
lay in contact with the nuclear membrane, or but a little dis- 
tance from it (fig. 5). However, they could decidedly be traced 
into centrally situated, intermingling, achromatic strands, 
their staining capacity undergoing a gradual diminution 
towards the interior. In many ova the germinal vesicle was 
at first sight homogeneous and devoid of chromatin (fig. 6). 
Though in some such cases the most careful research re- 
