TEE FCETUS. 



1029 



2. Pig. — The placenta is formed by an expansion of the villous tubercles, aa in Solipeds. 

 The ciiorion is not entirely covereil by tliese tubercles, but here and there it shows briglit little 

 patches, where its tissue is menly covered by an epitiitlial layer; it is also glabrous at those 

 points where it is in contict with the chorion of neighbouring foetuses. 



The chorion lias not a body and two coruua, but is merely an elongated sac, the two 

 extremities of whicli are in relation witli the adjacent foetuses. The inner face corresponds, 

 as in Ruminants, with the amnion and allantois. The latter is the same as in the Cow, though 

 it is very much sliortcr; the inner covering of this membrane c<.)ntains the glycogenic matter, 

 but that of the amnion has none. 



The umbilical venir.h, amnion, and cord, are also the same as in Ruminants. 



3. Carnivora. — Tlie placenta is a thick ginile. surrounding the middle portion of the 

 chorion. It has a livid colour in its midi lie, green on its borlers. When the green-ctdoured 

 matter is isolated, and treated witii alcohol and cldoroform, then submitted to certain rea'.;enta. 

 it uppeais to be identical with the colouring matter of the bile, and derived, as that is, from 

 the hsomoglobin of the blood. 



The allantois is disposed, in principle, as in Solipeds. 



The chorion is quite like that of the Pig with regard to form, but it is different with regard 



Kij. 5t}5. 



SEMI-DIAGRAMM.\TIC VERTICAL, SECTION' OF A MATEltNAI, COTYLEDON OF THE SHEEP. 



(^cr, Uterine sinus; e, epitlielial lining of the sinus; V, veins, ami c, flexuous arteries of the sub- 

 epithelial connective tissue 



to structure, as it hac no chora' plates v/ith mineral granules. Nothing is known as to the 

 organ which fulfils the function of these deposits. 



The umbilical wsicZe— which remains very developed at all periods of fcetul life— resembles 

 in shape the allantois of the Pig, being a transversely elongated sac included between the 

 amnion and the inner allantoid lamina, an^l provided at its middle portion with a naiTOW 

 pedicle, which is prolonged into the umbilical cord ; its walls are extremely vascular. 



The amnion is lined, internally, by the inner lamina of the allantois. 



The umbilical cord lias, as in Solipeds, an allantoid portion; but it is extremely short, and 

 enveloped in a wide fold of the allantois. 



Results.— The comparative examination of the disposition of the placenta may furnish 

 valuable indications as to the procedure to be adoptfd in practising artificial delivery; as the 

 surgical mancBuvres should necessarily vary with tlie extent and disposition of the points of 

 union existing between the uterus and the fcetal envelopes. 



With this practical object in view, we believe that it is useful to divide the domesticated 

 animals into two groups : those which have a simple, and those whicli have a multiple placenta. 

 The first group may be subdivided, according as the simple placenta is qeneral or local. 



