400 DISCOVERY REPORTS 



since during early lactation more blood appears to break away (Plate XLII, fig. 4). The 

 material collected did not cover the later stages of gestation. Sections were cut of the 

 uteri of six pregnant whales, and the foetuses present were all in comparatively young 

 stages, viz. Blue whales 0*55, 0-91 and 1-52 m.; Fin whales o-8i, 1-09 and 1-63 m. 

 Later in lactation the uterus returns to the resting stage shown in Plate XLII, fig. 5. 



Fig. 137 shows the uterus of a whale (Fin, No. 877, 13. vii. 26) in which ovulation 

 had taken place, i.e. there was a corpus luteum a in the ovary but no sign of a foetus 

 in the uterus. The capillaries at the edge of the mucous membrane appeared to be 

 dilated — they were more evident in this section than in any of the others — but they 

 contained no blood corpuscles, while vessels in the deep mucosa were full of blood. 



The change in size of the uterus at ovulation is due to the increasing supply of blood 

 and the congestion of the uterine tissue. If ovulation passes without fertilization the 

 uterus tends to return to the normal. If, however, pregnancy supervenes the congestion 

 remains, at least for a time. At parturition also it is congested and presumably it has 

 remained so throughout gestation. During lactation the uterus returns again to normal, 

 both in size and in condition of the mucosa. 



A number of smears of vaginal mucus from different whales were collected and 

 stained in an endeavour to trace the course of the generative processes. This method 

 was used with some success by Long and Evans (1922) in their work on the oestrous 

 cycle in the rat. Care was taken that no apparent injury had been done to the internal 

 organs in the whales from which the smears were taken, for blood for instance may 

 sometimes be present in the vagina as a result of injury by the harpoon. 



The whales examined were as follows: four immature (Nos. 191, 203, 187 and 192), 

 five mature "resting" (Nos. 184, 185, 208, 260 and 264), one recently ovulated 

 (No. 250), two pregnant (No. 253, foetus 1-52 m., and 

 No. 186, foetus 2-65 m.), and two lactating (No. 244, 

 uterus 22-0 cm., and No. 271, uterus 17-0 cm.). 



The results were constant although in this small number 

 of cases only the obvious differences in the cells occurring 

 in the mucus can be pointed out. 



In immature (Fig. 133) and resting mature whales the 



mucus contains small clumps of epithelial cells (portions 



of epithelium) and many isolated cells, some from the 



surface of the mucosa, others from the epithelium of the 



glands. In immature whales a few red blood corpuscles r.b.c. 



occur. The presence of epithelial cells may account in '^■sl- 



part for the absence of much of the uterine epithelium Fig. 133. Cells from vaginal mucus 

 „ , of immature whale, ep.c, epi- 



m sections of the mucosa. ^h^li^, ^^i,,. ^ ^i^ ^g„, f^om 



In regard to pregnancy a smear from a whale containing glands; r.b.c., red blood cor- 

 a foetus of 1-52 m. showed that the dominant cells were P"*^ '^^^ 

 red blood corpuscles with a few polymorphonuclear leucocytes. In a whale with a 

 larger foetus (2-65 m.) the mucus was very thick and few cells could be seen. Epithelial 



