AND PLACENTA OF THE ELEPHANT. 
349 
The allantois, coexpanding with the divergence of these trunks, developes its principal 
sac through two opposite interspaces, and the two smaller divisions at the intermediate 
interspaces. 
It may, perhaps, aid in the comprehension of this rather complex structure, if I here 
cite from the rough notes which I penned on the first examination of the connexions of 
the allantois ; — “ The urachus expands in an infundibular form into the allantois. About 
4 inches fi:om the infundibrdar commencement of the allantois an umbihcal vessel 
recedes fi’om the amnios towards the chorion, carrying with it a fold of the free and 
thickened margin ; this fold expands to 5 inches in breadth : the layers adhere together, 
but could be separated. Each of the other two hypogastric vessels carry similar folds of 
the allantois inwards, from the smTace of the amnion to the chorion, and the allantois is 
again reflected by three broad folds diverging from one centre upon the amnios of the 
opposite side. The amnios becomes blended with, or closely adherent to, the allantois 
about 3 inches from the umbilical cord ; prior or anterior to this part, the two mem- 
branes are connected by loose reticulated tissue.” 
I now proceed -with the description, which was written after a recognition of the 
nature of the several parts observed in the course of the examination. The primary 
branches of the umbilical vessels reach, first, the borders of the placenta, and then ramify 
in the substance of the placenta and upon the inner surface of the chorion, being sup- 
ported there, and more or less sm’rounded, by the continuation of the allantois which 
forms the so-called endochorion. 
Upon the endochorionic vessels are developed a number of flattened, oval or subcir- 
cular bodies {e, e), varying in diameter from an inch or more to half a line. On sepa- 
rating the chorion from the allantois, these bodies were found to belong entirely to the 
latter membrane. To the naked eye they present a compact, structureless tissue, of a 
grey colour. On dissecting one of the branches of an umbihcal vessel, upon which one 
of these bodies was developed, the vessel was found to pass on the chorionic side of the 
body without undergoing any apparent change in the passage, the body being developed 
from the allantois and from that part which forms the allantoic side of the sheath of the 
vessel. These bodies are most abmidant near the placenta, where they are separated 
from each other by interspaces often less than their own diameter. They are wider apart 
upon the non-placental part of the chorion, especially as they approach the poles of the 
chorionic sac. Their number on the unruptured division of the chorionic sac was about 
120. They are exclusively an allantoic development. Several small specimens occur 
on the free duphcatures of the allantois continued from the umbilical trunks near the 
placenta : in almost every case they are developed on the course of the large vessels, and 
are restricted, with few exceptions, to that part of the allantois which is in contact with 
the chorion, and which forms the endochorion of embryologists. The free surface of 
these peculiar bodies is smooth and pohshed, not villous hke the cotyledons of the Bu- 
minantia; from which they likewise differ essentially in projecting inwards towards the 
cavity of the allantois. 
