92 THE PHYSIOLOGY OF REPRODUCTION 



epithelium shrivel up at this stage, and, as a consequence, the 

 blood contained in the lacunae is poured into the uterine cavity. 

 The lacunae are very often close to the glands, so that when a 

 lacuna ruptures, a whole gland may be carried away in the 

 blood stream. The lacunas have no regular inner wall, but in 

 some places the processes of the stroma were observed to combine 

 together to form a kind of wall which appeared to resist the 

 further encroachment of blood corpuscles in the stroma tissue. 

 Leucocytes are very numerous (usually in the close neighbour- 

 hood of the ruptured vessels), some of them being described as 

 mononuclear, and some as having two, three, or four nuclei 

 (products of division). The proportion of leucocytes to red 

 corpuscles was found to be 2 per cent, of the former to 98 per 

 cent, of the latter in unruptured vessels full of blood, while in 

 ruptured vessels, from which blood had escaped, the percentage 

 of leucocytes was noted to be as high as 18*75. Heape does not 

 state, however, that basophil or eosinophil cells occur, such as 

 have been described in the uterus of the dog at a corresponding 

 stage in the cycle. Degenerative changes were noted in many 

 of the epithelial cells, and also in some of the stroma cells, certain 

 of which were seen scattered beneath the remains of the 

 epithelial lining. The stroma below the lacuna) was observed to 

 contain normal as well as shrivelled tissue, but the deeper parts 

 appeared to undergo very little alteration. 



VII. The Formation of the Menstrual Clot. At this stage 

 Heape describes " a severe, devastating, periodic action." The 

 entire superficial epithelium, portions of the glands or even a 

 whole gland, and a part of the stroma, with broken-down blood- 

 vessels and corpuscles, are torn bodily away, " leaving behind a 

 ragged wreck of tissue, torn glands, ruptured vessels, jagged edges 

 of stroma, and masses of blood corpuscles, which it would seem 

 hardly possible to heal satisfactorily without the aid of surgical 

 treatment." Heape is in no doubt as to the extent of the 

 denudation, differing thus from those writers referred to above, 

 who believe that the destructive process in the human female 

 does not extend beyond certain portions of the superficial 

 epithelium. The cast-off mucous membrane is termed by 

 Heape the mucosa menstraalis. The deeper tissue undergoes 

 no change, the blood-vessels therein being still possessed of com- 



