138 PATTEN. 
abundant all through the tissues about the median and lateral eyes and the 
olfactory organs, and I see no reason to doubt that they will be found as 
abundantly elsewhere. Kingsley failed to confirm the existence of these cells in 
the embryo, which is somewhat surprising, for in stage they form as conspicuous 
an object in sections and surface views as any other organ of the body. 
I expect to describe in more detail the history of these cells in another 
paper. I refer to them here to make clear the remarkable fact that in these 
degenerate embryos there is almost nothing left but a mass of these highly 
specialized and peculiar cells. The only thing remaining besides them are the 
ordinary yolk cells and the blastoderm, and even this disappears, as such, over 
the mass of cells under consideration. It is as though a mammalian embryo 
should gradually degenerate into a mass of cells consisting solely of osteoblasts, 
or muscle cells, or any other specialized form of tissue. However, it must 
not be assumed that other kinds of cells are during degeneration converted 
into the fibre cells. The latter merely persist as such after the others have 
disappeared. 
On careful study of one of the sections we see the fibre cells usually in ill- 
defined groups, with intermediate areas containing some nuclei, unquestionably in 
karyokinesis. Other nuclei, however, seem to have made preparations for division, 
but instead of doing so they break into numerous deeply stained globules, which 
become disseminated through the yolk, and growing fainter and fainter, finally 
disappear. 
A portion of a section through the embryo is shown in Pl. X, Fig. 89. Below 
the disc is a clear area containing a few yolk globules, and many degenerating 
nuclei and cells, apparently derived from the mass of cells above. 
