PHASES IN THE LIFE OF THE INDIVIDUAL 671 



while the internal generative organs enlarge and ripe ova are 

 produced by the ovary. 1 



In both sexes the purely physical changes of puberty are 

 accompanied by psychical ones which are no less pronounced. 

 Both kinds of change are dependent largely, if not entirely, 

 upon the functional development of the generative glands. 



In animals the general nature of the change which sets in 

 at puberty is similar to that occurring in the human species, 

 and the secondary sexual characters often appear for the first 

 time at this phase of life. Excepting in the case of the domestic 

 animals, little is definitely known concerning the respective ages 

 at which the different species become mature. Most fillies 

 come in use when two years old, and all by the time they are 

 three. Cows may come on heat when a year old, but it is best 

 to postpone service until three months later. A good deal 

 depends on nutrition, but even starved and backward cows will 

 receive the bull when fifteen months old. Sows will receive the 

 boar when eight months old, and sometimes two months earlier. 

 Sheep will breed at the age of six months (that is to say, lambs 

 born in the spring will breed in the following autumn), but the 

 practice is to be deprecated in the interests both of the ewes 

 themselves and of their lambs. Dogs will breed when about 

 ten months old or even earlier (sometimes seven), but the larger 

 kinds do not breed so soon. Cats are similar. Rodents may 

 breed when still younger, but whether they do so or not depends 

 upon the season of the year and other conditions of environment 

 and nutrition. 



1 Runge (E.), however ("Beitrag zur Anatomic der Ovarien Neugeborener 

 und Kinder von der Pubertatzeit," Arch. f. Gyncik., vol. Ixxx., 1906), states 

 that growing follicles are by no means uncommon in ovaries of young 

 children. In the first year of life he found follicles of considerable size, 

 and in the second year still larger ones, some having a diameter of 135 /x. 

 In the third year degenerate follicles were also found. During this and the 

 following years there was a progressive increase in the size of certain of 

 the follicles until the ovaries became scarcely distinguishable from those 

 of adults excepting for their smaller size. Runge states further that in one 

 instance he found a corpus luteum in an ovary of a recently born child, but 

 this must be regarded as very exceptional. As a result of his observations, 

 Runge concludes that follicular maturation sets in daring infancy and not 

 at puberty. Ovaries of human embryos showed growing follicles only in 

 very rare instances. 



