346 A. A. W. HUBRECHT. 
in their wake ; others have particularly insisted on the forma- 
tion of special nutritory fluids in the decidua to which the 
name of uterine-milk has been given. I will not here further 
discuss the value of these different views. It is probable that 
the arrangement as we find it in the hedgehog may also throw 
light on certain aspects of this question, which is much more 
of a physiological than of an anatomical or histological nature. 
To study the deciduofracts in the fresh state should be 
specially recommended to anyone who might feel attracted 
by the subject: to compare them—also in the fresh state— 
with large cellular elements carrying large nuclei that are 
found in the decidual tissue of the mouse and of other rodents, 
would be at the same time particularly necessary. Itis not my 
intention to inquire into their nature any further myself, and 
I hope the subject may soon be taken up by someone who is 
better fitted for the task. The hypothetical functions which I 
have ascribed to the deciduofracts, will then, perhaps, not stand 
the test of crucial examination. I hope, however, that it may 
be recognised that in the present state of our knowledge this 
hypothesis recommends itself by several arguments. 
I cannot conclude this chapter on the physiological pheno- 
mena connected with the placentation of the hedgehog without 
having called attention to the fact that the discoidal after-birth 
was more than once found by me in the female generative organs 
shortly after parturition. It is thus totally enucleated, and 
in this respect important differences exist between hedgehog 
and mole. In the latter mammal I find that the larger portion 
of the placenta remains attached to the maternal tissues, and 
that instead of being shed, as in the hedgehog, it is gradually 
submitted to a process of resorption by which it becomes 
smaller and smaller, and finally disappears. I need not say 
that these swellings in the mole’s uterus after parturition, 
which are nothing else but placental tissues on their way to 
resorption, give to the uterus the false aspect as if it contains 
embryos. Only it will be understood that here the smaller 
swellings are actually the later stages. A continual series of 
the process here referred to is in my possession. I will reserve 
