16 BULLETIN: MUSEUM OF COMPARATIVE ZOÖLOGY. 
217, 229, 413, 418), Stuhlmann (86, Figs, 228, 233), and Moore 
(93, Fig. 1). 
The terminology which 1 have used is that of La Valette St. George, 
as adapted by Boveri: — 
Spermatogonium Hertwig’s Ursamenzelle. 
Spermatocyte, 18t order — P Samenmutterzelle. 
Spermatocyte, 2d order = 5 Samentochterzelle. 
Spermatid = i Samenenkelzelle. 
Spermatozoón, 
G. W. Field (93) uses a terminology which seems to admit one less 
spermatocyte stage than is recognized by authors generally: “We find 
that the largest cells, the spermatogones (using the nomenclature pro- 
posed by La Valette St, George and now very generally adopted), 
divide by mitosis and form two spermatocytes. Next each spermato- 
cyte divides, also by mitosis, forming two spermatids, Each ‘spermatid 
then changes directly into the spermatozoón, without further division, 
Thus each spermatogone gives rise to four spermatids.” Field uses this 
apparently as a general scheme of spermatogenesis. ‘ Spermatogones ” 
are, I suppose, spermatogonia. But they are not “the largest cells” in 
Boveri’s scheme, nor do I find that La Valette St. George or any other 
author has applied the term to these large cells, which Boveri desig- 
nates as spermatocytes of the first order. The spermatogonia after they 
have ceased dividing as spermatogonia become by a process of growth 
spermatocytes (Boveri's spermatocytes, Ist order). Field’s “ sperma- 
togones" therefore probably correspond to Boveri's spermatocytes of 
the Ist order, his “spermatocytes” to Boveri's spermatocytes of the 
2d order, and the spermatogonia of Boveri are unmentioned. Field has 
therefore extended the use of the term spermatogonia to cover the whole 
period of that cell generation which Boveri calls at its beginning the last 
generation of spermatogonia, and during the rest of its existence sper- 
matocytes: of the first order; consequently he designates as a spermato- 
gonium division one that Boveri calls a spermatocyte division. It is 
difficult to see why the fact that “each spermatocyte divides also by 
mitosis” need be so strongly emphasized. It would be much more 
strange if the spermatocytes divided amitotically (compare vom Rath 
'91 and '93, and Ziegler. '91). 
Henking (91) in his paper on Pyrrhocoris has considered the origin 
and fate of the chromatic rings. His Figures 13-20 show stages in the 
formation of the rings. Henking differs from most other authors in 
denying that there is any doubling of the chromosomes between the last 
