570 
J. BRONTE GATENBY. 
the same generation. This is never the case further down 
the lumen. We then come to one of the most remarkable 
facts which I am able to point out in this paper. It is that 
the spermatocytes, etc., in different parts of the lumen are of 
different generations and derived in a varying manner, and 
that they show this by their appearance, which is character- 
istic in every case. 
If PL 31, figs. 10, 11, 17, 19, 20, and PI. 32, fig. 24, be 
inspected it will be seen that very remarkable differences 
exist between the cells here drawn ; all these figures are to 
the same scale and the cells were all found in the germinal 
epithelium. The same remark about differences applies to 
PI. 30, fig. 6, PI. 32. fig. 21, and PI. 33, fig. 30. These are in 
a characteristic stage of the prophases of the heterotypic 
division, and not only do figs. 6 and 21 differ markedly in 
their nuclei, but the cytoplasmic inclusions are quite distinctly 
unlike in each example. 
In the same way, if the cell divisions drawn in PI. 32, 
fig. 22, PL 32, fig. 28, and PL 33, figs. 34 and 39 be compared 
it will be noticed that the cytoplasmic inclusions behave 
differently and are different in size and shape. If the sper- 
matocyte in PL 32, fig. 25, be compared with that drawn in 
PL 33, fig. 32, and the spermatid in PL 32, fig. 24 a, with that 
in PL 33, fig. 36, it will be seen that remarkable differences 
exist. This brief recital of some of the curious facts which 
are to be found in the ovotestis of Helix at once serve to 
show that the problem of the derivation of the various sex 
cells from the indifferent cell is a very difficult matter to 
understand, and one which has been inadequately treated. 
I should hasten to make it quite clear that this paper does 
not by any means completely describe all the sorts of cells 
found in the ovotestis. For myself, I consider that the many 
months of close attention which I have devoted to this work 
have only served to show me that a complete explanation of all 
the various cell generations in the snail's gonad is not the 
work of months, but of years. It will need the collection of 
a complete series of sections of gonads for every month of 
