PROFESSOR W. TURNER ON THE PLACENTATION OF THE APES. 
545 
with an opaque epithelium, also referred to, were so sparing in number that they 
were very seldom seen. As the uterine glands in the non-gravid Semnopithecus are 
much more numerous and more distinct than in the non-gravid Macacus, it is possible 
that in the former animal they may during gestation undergo a smaller amount of 
change both in form and structure. The spongy character of the decidua vera in the 
human uterus was much more pronounced than in the uterus of Macacus cynomolgus. 
I am unable to say if the decidua vera is shed in parturition in the Macacus or 
remains on the surface of the muscular coat. 
In the absence of any information of the early stages of gestation in the Apes, it is 
not possible to say with certainty that the impregnated ovum is in the early weeks of 
pregnancy shut off from the general cavity of the uterus, and confined in a special 
ovigerous chamber by the development of a periovular decidua, the decidua reflexa, 
like that of the human female. M. Breschet, in his figures of the placenta and mem- 
branes within the gravid uterus of the two specimens of Cercopithecus sahceus which 
he described, has represented the decidua as divided in some places into two layers, as 
if one were the vera and the other the reflexa. Professor Owen, in his description of 
the shed placenta of Macacus rhesus , states" that portions of the deciduous membrane 
remain attached to the outer surface of the placenta and chorion. Dr. BollestonI' 
was unable to say, from the condition of his specimen, if the decidua reflexa was 
as complete as Breschet had described and figured. 
From the observations of these anatomists it would seem that, in their judgment, 
the Apes possess a decidua reflexa, although the demonstration of its arrangement 
does not appear to have been very complete in any of the specimens. Still, from the 
general similarity, both in form and structure, of the placenta in the Ape and the 
human female, there is every probability that a reflexa grows around the young ovum of 
the Ape, as it does in the human uterus. My dissection, however, proves that in the 
later stages of gestation, the chorion and uterine decidua have become so intimately 
attached to each other, that the demonstration of the decidua reflexa as a distinct 
layer is not possible ; and during parturition, if the chorion had carried away, on its 
outer surface, a covering of decidua, it would have been difficult to say if that covering 
were reflexa or vera. This, however, is no proof that a reflexa did not at one time exist 
as a definite layer, for, as I have already stated, even in the human uterus, in the later 
months of pregnancy, the chorion, with its covering of reflexa, becomes closely attached 
to the corresponding surface of the vera. Moreover, the reflexa cannot, as was at one 
time supposed, be regarded as an exclusively human structure ; for, as I have else- 
where shown, | it exists as a definite layer on the surface of the non-placental part of 
the chorion of the two-toed Sloth, Cholopus Hoffmanni. 
Both in the human placenta and in that not only of M. cynomolgus but of the other 
monkeys described by previous anatomists, a well-defined and even tolerably thick 
* “ Catalogue of the Museum of the Royal College of Surgeons,” Physiological Series, vol. v., p. 145. 
t Trans. Zool. Soc., vol. v., 1863. J Trans. Roy. Soc. Edinburgh, 1873, p. 77. 
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