io6 THE PHYSIOLOGY OF REPRODUCTION 



than in the deeper tissue. Thus, although leucocytes are probably 

 involved in the process of pigment formation, there is no need to 

 assume thit they carry the extravasated corpuscles to the region 

 where pigment is most abundant. Sometimes the interior of the 

 uterus appears superficially to be perfectly black with pigment, but 

 in such cases the pigment is, no doubt, derived from blood which 

 had been extravasated during a series of proccstrous periods, and 

 not merely during the most recent one. Assheton l states that the 

 pigment so formed is subsequently disposed of. 



('..rner* has described cyclic changes in the utems of the sow. 



.lust before oestrus there is evidence of activity on the part of the 



epithelial cells in which mitotic figures may be found, while a contrary 



process is manifested here and there in nuclear chromatolysis and 



inerate changes, and neutrophilic polymorph leucocytes in the 



epithelial stronia become very numerous. During ccstrus the 



-,a is very o-dematous. The post-oestrous changes are very 



marked. The epithelial cells actively secrete a serous thud from the 



h to the tenth day, after which they subside to a cuboidal form, 



and there is a slow reversion to the oestrous type. Post-u?strous 



glandular hypertrophy is not definite, but otherwise the changes are 



ly .-.litest ive of an abbreviated pseudo-pregnancy occurring 



under the intluence of the corpus luteum of the ovary (see above, 



pp. ( .t!t-HU. and b.-l-.w. pp. :'.71-:'-72). 



TIIK ( 'v I.K IN M.\i;sri'iAi.s 



The changes whi<-h occur in the internal generative organs of 



the Marsupial cat (Ditxi/oru* mvarrinus) have been described fully by 



Hill and O'Donoghue (see p. :'- ( i). Tin- prou-strum lasts for from 



four to twelve days, and during this time the uterine rnucosa 



increases in thickness and becomes more vascular, while its glands 



lengthen and become convoluted and the epithelium tends to 



thicken. huring "-st nis. which lasts one or two days, the changes 



tie continued. Following o-strns there is, according 



to these authorities, a ) US period lasting five or six days 



terminated l.y ovulat ion, and during which the uterine changes 



lime further. This is followed by either pregnancy or pseudo- 



huring pseud-)- pregnancy the uteri enlarge considerably 



and become -till mop- .;, and these chan-es are succeeded by 



deg- |uain:ition of epithelium with extravasation of 



' : Ogolftte I'hi.-.-nta." /'///'/. Tr<in*., B., 



vi.l. <-\i viii.. i I, tlii- utt-rinc iniii'-isa liavc also l.ccn descrilicd in 



. .'I,,,,,/., \\t\-2 ; and <;.-ist. I'.M:',. foe. <'<(. 



MM! I't.-i-Ms ..f tin- Sow, etc.* 

 iii.-i-- Institute (Washington) Piiblica- 

 '' 



