THE MULTIPLE TESTIS OF URODELES. 



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cm. 

 11 

 10 

 9 

 8 

 7 

 6 

 5 





B 



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12 13 14 



CHART 2. Graph A illustrates the relation of testis structure to size in 

 the 93 Desnwgnathns males listed in Table I. The structural types from 

 the first column of this table (see chart i, Figs, i to 14) are here used as 

 abscissae, and the corresponding average lengths from the last column are 

 used as ordinates. Between stages 5 and 14 an increase in length of but 

 1.2 cm. is indicated; the number of lobes of the testis increases with age, 

 while the body size, after a certain period, remains relatively fixed. Be- 

 tween stages i and 5, on the other hand, there is an increase in length o f 

 4.4 cm. Males mature spermatozoa long before they have attained their 

 maximal size; the processes that operate to produce a multiple testis begin 

 at sexual maturity; hence the development of the first additional lobe is 

 accompanied by the continued increase in body length. 



Graph B, constructed in the same manner as Graph A, shows the rela- 

 tion of testis structure to size in the 24 animals listed in Table II. Be- 

 tween stages 5 and 12 there is here a variation of only 0.3 cm. in average 

 length, as compared with the increase of 1.4 cm. between stages 2 and 5. 

 These animals average much smaller than the animals of the first group, 

 as may be readily seen from the relative heights of the curves at any point. 

 Running out of anterior lobes occurs relatively early and comparatively few 

 lobes are developed; note that stages g to 14, represented by 13 males in 

 Table I., have but one representative in Table II. 



streams are the largest found in the vicinity of Ithaca, and are 

 uniformly of a lightly colored type. Animals taken from the vari- 

 ous gorges nearer Ithaca are ordinarily of smaller size and darker 

 coloration. These have been grouped separately and a second 

 graph (B) constructed which agrees in general with the first. For 

 data concerning these animals, see Table II. The animals in this 



