446 Development and Vascularization of the Testis 
The measurements were made regardless of whether the sex gland 
was male or female, although in embryos beyond thirty-three mm. in 
length this sex distinction is observable. 
In the adult pig testis the measurements vary considerably. The 
average might be placed at sixty-five mm. long, forty-two mm. deep and 
thirty-seven mm. wide with an average weight of sixty-eight grammes. 
These results are of interest when compared with those obtained by 
Krause‘ for the human adult sex gland. His averages were thirty-seven 
mm. long, twenty-eight mm. deep and twenty-four mm. wide, with the 
weight falling fifteen and twenty-four and a half grammes. 
Development of the Blood Supply.—Concerning the embryonic devel- 
opment of the testis much has been written and it seems useless to enter 
into a discussion of the histogenesis and descent of the gland. Among 
the more recent studies of these subjects the article by Allen® on the 
ovary and testis of mammals will be found to contain a comprehensive 
survey of the literature and in this monograph the author outlines 
minutely the growth of the testis of the pig. He. however, makes no 
mention of the blood supply. 
The first macroscopic indication of the vascularization of the testis 
is found when the embryo pig is thirty-three mm. in length. At this 
time the sex gland is situated relatively lower on the mesial surface of 
the Wolffian body, which may to some extent account for the low level 
at which the spermatic artery arises from the aorta. Concerning the 
origin of this artery there has been some discussion as to whether at 
times it may arise from one of the lower Wolffian arteries. Of the 
seventy-five or more specimens ranging in length from twenty-five mm. 
to two hundred and twenty mm., only one was found in which the artery 
arose otherwise than from the aorta. In this exception the spermatic 
artery came from the most caudal Wolffian artery close to its origin from 
the aorta. 
In the thirty-three mm. stage seen in Fig. 1 no convolution is ap- 
parent in the spermatic artery which courses ventral to the Wolffian 
arteries. In this figure, as well as in the two following ones, it was 
found advisable to lay back the Wolffian body from its normal position 
in order to more clearly demonstrate the vascular supply to these glands. 
The renal artery which penetrates the kidney when the embryo is twenty- 
eight mm. in length is quite prominent and a few glomeruli are seen 
7Krause, W.: Zum Spiralsaum der Samenfaden. Biol. Cent., 1881. 
8 Allen, B. M.: Embryonic Development of Ovary and Testis of Mammals. 
Am. Jour. Anat., Vol. III, No. 2. 
