THE REPRODUCTIVE ORGANS 



383 



(a) Growth of the Ovaries 



In discussing the physiology of the ovaries it will be convenient to start with an 

 account of their growth in the foetus and the young whale. In Blue and Fin whale 

 foetuses measuring about i m. they are small elongated bodies whose flattened surfaces 

 are marked by a number of furrows (Fig. 118). The whole genital tract of the young 

 foetus at this stage is engorged with blood so that the ovaries are of a deep red colour. 

 In larger foetuses the furrows are more pronounced and more numerous (Plate XXXIX, 

 figs. 3 and 4). After the calf is born the majority of the furrows are smoothed out by the 

 growth of the ovaries, but some remain to mark the convolutions of the adult ovary 

 which are referred to above, and some of the minor furrows occasionally persist to 

 give the surface of the ovaries a curious appearance which has been described in notes 

 on the internal genitalia as "bramble-marking." This is illustrated in Fig 119 and 

 Plate XXXIX, fig. 4. 



Fig. 118. Ovary of foetus 

 measuring 1-13 m. 

 (Natural size.) 



Fig. 119. Small portion of ovary of 

 immature w^hale, showing "bramble 



markings." x 1-5. 



Although the ovaries do not grow very much from birth to sexual maturity, consider- 

 able changes take place. From rather rounded, soft structures they become pale, flat, 

 compact organs (Plate XL, fig. i). They remain, however, small up to this 

 stage, for in Fin whales measuring less than 18 m. and in Blue whales under 20 m. 

 the two ovaries together weigh less than i lb. The ovaries of immature Fin whales 

 practically never weigh more than 2 lb., nor those of Blue whales more than 3 lb. 

 After sexual maturity is reached the weight of the ovaries, as shown in Figs. 120 and 

 121 , appears to increase up to a point with the increasing length of the whale. Although 

 the ovaries of large whales are as a rule bigger than those of smaller whales, the increases 

 illustrated in these graphs are in reality due more to the presence of a larger number 

 of old corpora lutea than to an increase in the actual size of the ovary. When a corpus 

 luteum of pregnancy is present the weight of the ovary may be nearly doubled, so that 

 in connection with the growth of the ovary, only those of non-pregnant females can 

 be taken into consideration. 



