THE PROBLEM OF REJUVENATION 



487 



to the question whether besides a general improvement and a 

 regeneration of sex characters there is also a prolongation of 

 life, the experiments do not provide data. 



If a unilateral operation only is made, the regenerated 

 animal can fecundate. According to Steinach, regeneration 

 of the generative part also in the testicle may take place in the 



Fig. 140. — "Rejuvenation" oj senile dog, 18 years old. — Same as 139. The 

 animal is only able to stand for a short time, and has to be supported. — 

 From Wilhelm, 



senile animal. Similar statements as to the generative part 

 have been made, as already mentioned, by Harms and Voronoff 

 about the results of testicular transplantation in senile animals. 

 Steinach states that he succeeded in regenerating female rats 

 by ovarian transplantation. An example may be given. A 

 female rat 26 months old, which was sterile for 10 months, and 

 showed no signs of heat and revealed hairless patches on the 



