3H 
BULLETIN OF THE BUREAU OF FISHERIES. 
In the following description of the genesis and structure of the sperm cell of the 
lobster, I shall follow in the main the account of Koltzoff (172), from which I have con- 
structed a number of diagrams (fig. 31 , i-j, and fig. 32). This account, whether correct in 
all particulars or not, is at least intelligible, and we are able to understand the remarkable 
evolution in form which these cells undergo in consequence of changes in osmotic pressure. 
It is very different from that of Sabatier, who devotes 37 pages to the sperm cells of the 
lobster, yet leaves it difficult to understand his descriptions and impossible to construct 
any consistent diagrams from his figures. 
Fig. 31. — Diagrams of sperm cells of the lobster before (i), during (2), and after (3) capsular explosion, based upon Koltzoff (see 
172). a a, plane of section in figure 36; a. ch., anterior chamber; deb, distal central body; Ex. sub., external layer; in. t., 
inner tube; med. t., medium tube; n. proc, neck process or ray; p c b., proximal central body; p. ch. t posterior chamber; 
p. mb., outer protoplasmic (?) membrane. 
According to Koltzoff the sperm cell is derived by metamorphosis from a spermatid 
which in turn arises by division from a spermatocyte of the testis. The centrosome 
divides into two parts, and for some time remains united by fibers to the nucleus. The 
cell body is stuffed with granules which exhibit a difference in staining power, and in 
fact become differentiated into two important parts of the sperm, the mitochondral 
body and the capsule. 
In the course of these changes the mitochondral becomes pressed against the 
nucleus, and molded upon it. A vesicular sperm cell is thus formed, peculiar to the 
