Ti DR. J. W. JENKINSOX ON THE [Feb. 6, 



valuable food for the developing foetus ; not only can the tropho- 

 blast be shown to be absorbing fat even while the blastocyst is 

 still floating freely in the lumen of the uterus, but the cells of 

 this foetal membrane are also phagocytic and actively ingest the 

 solid particles of the uterine milk. This food -material is of 

 maternal origin ; fat is secreted by the uterine epithelium and 

 glands, the red blood- corpuscles are exti'avasated from superficial 

 capillaries, while the leucocytes emigrate through the epithelial 

 cells, the Stabchen are formed by the cells of the maternal epi- 

 thelium, and the degenerating cellular masses result from the 

 extensive disintegration of epithelial and subepithelial tissue. 



More recently the studies of Kolster on the placentation of the 

 Horse, Cow, Sheep, Pig, Roe-deer, and Red-deer have thrown 

 additional light on the mode of manufacture of this valuable food- 

 supply. ^ 



This author, while fully corroborating Bonnet s account or the 

 secretion of fat in the extra- cotyledonary uterine epithelium 

 and its glands, and of the copious emigration of leucocytes through 

 the epithelium dui-mg the greater part of gestation, has given a 

 more detailed description of the histological nature of these and 

 other processes. In fat-secretion the outer end of the cell with 

 the fat-globules it contains is protruded into the lumen of the 

 uterus or of the gland, pinched off, and ejected ; exactly the same 

 process, which evidently resembles very closely the foi-mation of 

 milk in a mammary gland, occurs in the secretion of fat in the 

 crypts of the maternal cotyledons. The fat so secreted is quickly 

 absorbed by the trophob!ast. 



Another very interesting phenomenon described by Kolster 

 is the production by the glands of a " cellular secretion," in 

 addition to the thin coagulable liquid substance usually found 

 in them ; here and there small tracts of the epithelial wall 

 become invaginated into the gland-lumen, and being cut off 

 degenerate and are ejected by the mouths and added to the 

 uterine milk. The epithelial cells so cast out are often accom- 

 panied by connective-tissue corpuscles and leucocytes. Bonnet 

 has recently demonstiated a similar " cell -secretion " in the 

 uterine glands of the bitch. These ejected gland-cells form 

 a very important though not an only source for the cellular 

 constituents of the milk. Considerable masses of disinte- 

 grating maternal tissue are added to the whole, as well as 

 quantities of red coipuscles. All this material is ingested by the 

 phagocj^ctic trophoblast ; the foetus is thus able to obtain a large 

 amount of proteid food and — from the red corpuscles — the 

 essential iron as well. The result of the intra-trophoblastic 

 digestion of the haemoglobin is the formation of pigment-masses 

 in the cells of this layer ; these masses will sometimes give an iron 

 reaction, but usually not. The pigment was not further investi- 

 gated by Kolster. A very similar pigment is formed by the 

 extravasation of blood from subepithelial capillaries at the time 

 of heat, the blood-corpuscles being taken up by wandering cells 



