106 



third year. Tlio testis having strongly increased in size during liiis 

 time, it is impossible that several teslis-ampnliae have fnsed to form 



such a canal system. On the 

 contrary, we mnstconclnde 

 from the stages, described 

 above, that the testis tubnles, 

 which are originally simple 

 and vei-y short and which 

 are called testis ampullae 

 then, divide towaid the 

 peripliery into a number 

 of tubules and that these 

 branches are connected with 

 the rete by the proximal 

 part of the ampulla. On 

 p.^ ^ comparing the different sec- 



Section of the testis of a frog of the third tions ') we see that both 



year; the rete is partly visible (X 50). length and diameter of the 



seminiferous tubules have strongly increased. 



Turning now to the testis of the adult frog, we observe almost the 



same here. In figs. 8 and 9 parts of two frontal sections of the left 



testis (long 10.5, broad 7 nim.)of 



an adult common frog (length 



6.3 cm.) are reproduced. The 



tracing of the course of the strongly 



ramified testis tubules and the 



graphic reconstruction of this taking 



too much time, I can only des- 

 cribe a few tubules, not very 



strongly branched. They are 



reproduced in tigs. 8 and 9 and a 



reconstruction of the same tubules, 



beside each other and in one Fig. 7. 



plane is given in fig. 10. This had Section as in fig. 6, but about half- 



to be done, because the tubules, way the periphery (X 50). 



winding too much around each other, especially in the neighbour- 

 hood of the rete, could not be reproduced, projected on a certain 



plane. ' 



The tubules, designated A I and A 11 in fig. 8 do not branch 



1) Originally I had the intention to reproduce all the figures at the same magni- 

 fication (X 100) ; this proved impossible, however, the figures of immature frog- 

 testes then becoming too small and those of adult frog-testes becoming too large. 



