595 
The muscle-fibre is of course not included in the testis. Whether 
it usually continues to exist after the change in function of the cell 
could not be determined. In later stages a muscle-fibre is often found 
adjoining a developing testis but it is impossible to be certain that 
that particular fibre belonged to the cell from which that testis 
developed. 
In one case, however, 
indications of degeneration 
of the fibre were observed. 
In Fig. 6 the outline of a 
muscle-cell containing three 
nuclei, two of which are the 
products of recent division, Fig. 6. 
is shown. Here the muscle- 
fibre was apparently breaking up into granules. In some of the other 
cells (Figs. 2 and 3) apparent breaks in the muscle-fibre may be in- 
dications of beginning degeneration. 
But not all of the muscle-cells give rise to testes, nor do all the 
testes arise from muscle-cells. There are in this region of the paren- 
chyma many other smaller cells with fibrillar prolongations: and among 
these many lying in the testis zone begin to divide, amitotically in 
almost all cases, and also give rise to testes. Figs. 7 and 8 show 
two such cases. In Fig. 7 the two portions of the dividing nucleus 
stain differently. In these figures the cytoplasm is indicated merely 
by an outline because the whole cell body is homogeneous and without 
the large spaces characteristic of the muscle-cells. The cytoplasm, 
however, stains deeply like that in the young testes arising from the 
<P. OY 
Fig. 7. Fig. 8. 
muscle-cells. These cells are ordinary parenchymal cells and are not 
so evidently differentiated as the muscle-cells but they are in no 
way visibly different from other parenchymal cells which do not give 
rise to testes. 
The later growth of the testis consists in increase of the number 
of nuclei, usually by amitosis, the development of a membrane and 
38* 
