4i8 DISCOVERY REPORTS 



CONCLUSIONS SUMMARIZED 



The conclusions advanced in this paper may be summarized as follows : 



1 . Ankylosis of the epiphyses starts from both ends of the vertebral column, but 

 anteriorly it does not proceed much beyond the cervical series. Ankylosis is completed 

 among the anterior thoracic vertebrae. 



2. Complete ankylosis — that is, physical maturity — bears little relation to length, but 

 is found when more than fifteen corpora lutea are present in the ovaries. 



3. All ovulations are permanently recorded in the ovaries. 



4. Because whales act collectively the number of unfertilized ovulations before preg- 

 nancy tends to be the same in any one season, and this manifests itself in the greater 

 frequency of certain numbers of corpora lutea than others. 



5. Each peak of the frequency graph represents an age group at an interval of two 

 years from the one previous to it. 



6. There are three peaks in the frequency graph before the physically immature 

 whales give place to the mature. This indicates that physical maturity is attained when 

 whales are from six to eight years of age. 



7. No signs of a climacteric have been observed in whales up to twenty years of age, 

 but there appears to be a sexual "prime" at ten years, after which the size and weight 

 of the ovaries diminish. 



