684 CLARENCE L. TURNER 
knowledgment is also made to Mr. Leo Massopusst, artist at 
the Marquette University School of Medicine, for instruction in 
his method of illustrating. 
Ill. ANATOMY OF THE TESTIS 
1. General relationships 
The testes are two elongated white bodies situated in the pos- 
terior part of the body cavity just ventral to the swim bladder. 
They fuse together at their posterior ends, forming a single 
body. They are oval in shape and taper toward their posterior 
ends. Usually they are about equal in size, but cases have been 
noticed in which one testis was nearly twice the size of the other. 
They are attached to the swim bladder by two delicate mesorchia 
which converge posteriorly into one at the point where the testes 
fuse. Anteriorly the mesorchia extend beyond the limits of the 
testes and support a sheath containing the genital arteries and 
veins. 
Posteriorly the testes communicate with the urogenital open- 
ing by a thin-walled but capacious sinus. <A horizontal septum 
separates this sinus from a dorsal chamber which receives the 
common ureter from the Wolffan bodies. Both chambers ter- 
minate in the common urogenital opening. 
2. Volumetric variation 
The volumetric variation of the testis from one season to 
another is a conspicuous feature. Just after the spawning sea- 
son, which occurs in late April or early May, the testis is de- 
pleted and its volume is slight. During May, June, July, and 
early August there is practically no change, except for a slight 
individual variation. Late August witnesses the initiation of a 
sudden increase in volume, which proceeds so rapidly that by 
the latter part of September the weight is between thirty and 
thirty-five times as great as it was six weeks earlier. By Janu- 
ary the maximum weight has been attained, when it is nearly 
forty-five times as great as the weight of the depleted testis. 
At this time it represents from 4.58 to 5.9 per cent of the entire 
eross weight of the body. 
