1891.7 Embryology. 285 
Dec. 16, 1890, what promises to be an important contribution to that 
most interesting problema magnum. 
Regarding the recent work upon the actual ontogenetic changes 
taking place in the human embryo as insufficient for explaining the 
true morphological descent of the testis in the Mammalia, the author 
returns to the comparative methods of Hunter and others, and ulti- 
mately sees reasons for associating this change of position with changes 
in other organs,—namely, mammary glands. 
From the position of reproductive glands, Wolffian body and body- 
wall in many mammals the gubernaculum is found to be a complex 
structure, not entirely homologous in different groups. Thus the testis 
is first attached to the Wolffian body; only later does the latter 
become connected with the body-wall by a special ‘‘ inguinal liga- 
ment,” which is connected with a peculiar inward process of the mus- 
cular body-wall, an ‘‘ inguinal cone.’’ The separateness of these three 
parts of a complex gubernaculum is shown in the adult Monotremes. 
The phenomena occurring in the periodic descent in the rodents 
and insectivores furnish the starting point for the interpretation of all 
other groups. 
Here the gubernaculum is chiefly a much-enlarged ‘ inguinal cone,”’ 
or modified ingrowth of transverse and internal oblique muscles (cre- 
master). Pari passu with the descent of the testis in the adult occurs 
the evagination of this cone to form a scrotal pouch, This descent 
appears to correspond to the period of enlargement of the testis ; the 
withdrawal into the body to the period of enlargement of the mam- 
mary glands of the female, 
In lemurs, apes, and man secondary changes have resulted in the 
occurrence of the descent once for all in the embryo. Even here the 
“ inguinal cone,” though not playing so important a part, in the single 
descent has muscles resembling those in the rodent. The preforma- 
tion of a scrotum independent of the descent is not found in all 
these animals so markedly as in man, where it is to be regarded 
as a newly acquired falsification of the true record of sequences, and 
one that is here alone transferred to the female (in the form of the 
labia majora). 
n man, again, an interesting exception to the lack of periodicity 
occurs,—a reminiscence of a previous adult rodent-like condition 
being represented by two successive descents in the embryo. Thus a 
temporary descent has already taken place in embryo of eight cm. 
This is followed by what is interpreted as a true reditus testium, 
