Bauhaus-Universität Weimar

Titel:
The Cyclopaedia of Anatomy and Physiology, vol. 3: Ins-Pla
Person:
Todd, Robert Bentley
PURL:
https://digitalesammlungen.uni-weimar.de/viewer/image/lit29464/329/
MARSUPIALIA. 
them at the utmost) capable of taking refuge in 
her pouch.” * 
Besides the satisfactory evidence, thus afforded 
by different and independent observers, respect¬ 
ing the condition of the mammary fœtus and its 
true relations to the nipple, the discovery of the 
uterine fœtus was announced nearly at the 
same time by two naturalists in two different 
species of marsupial animals. Mr. Collie, 
whose experiment on the young mammary 
fœtus of a Kangaroo has just been quoted, 
states in the same letter, “ I have just now 
procured two gravid uteri, (of the Macro¬ 
pus Brunii,) in which fetuses seem to be 
arrived at, or very near to, the termination of 
the period of gestation. One of them, which 
is about the size of the smallest young already 
mentioned, which was about one-half larger 
than the body of the common wasp, as being 
in the abdominal sac, has protruded through 
an opening inadvertently made in the uterus, 
and is distinctly seen through its transparent 
membranes and the liquor amnii.”f About the 
same time Dr. Rengger, a naturalist who was 
detained several years by the Dictator Francia 
in Paraguay, gave the following account of the 
generation of a species of Opossum ( Didelphis 
Azarœ) in his work on the Mammalia of that 
province. “ The fetuses are developed in the 
cornua uteri, and not in the lateral canals. 
Some days after impregnation they have the 
form of small round gelatinous corpuscles, 
which do not appear, even when examined 
with a lens, to have any communication with 
the mother, but a red line indicates the first 
commencement of development. Towards the 
end of gestation, when the fetuses have attained 
the length of six lines, they are seen to be en¬ 
veloped in a membrane and provided with an 
umbilical chord, which is united to the uterus 
by the medium of many filaments. The head, 
the four extremities, and tail are recognizable 
with the naked eye, but those fetuses which 
are nearest the Fallopian tubes are generally least 
advanced. “ In gestation they make the circuit of 
the lateral canals, in which they are found to be 
deprived of their fetal envelopes, and to have 
no communication with the parent by means of 
the umbilical chord; whilst one fetus was 
found in this situation, two others were still in 
the body of the uterus (vaginal cul-de-sac), 
from which the umbilical chords were not yet 
detached. At this period a slight enlargement 
of the cul-de-sac and lateral canals was the 
only change perceptible in them.”! 
Thus, by the various observations derived 
from the different sources above indicated, the 
following propositions are satisfactorily esta¬ 
blished, viz. that the young of the Marsu- 
pialia are developed, primarily, as Tyson con¬ 
jectured, in the true uteri or cornua uteri ; but 
that, contrary to Tyson’s opinion, they are, as 
* Barton, ' Facts, Observations, and Conjectures 
relative to the Generation of the Opossum/ Annals 
of Philosophy, vol. vi. 1823, p. 349. 
t Zoological Journal, vol, v. p. 240. 
t From the Analysis of Rengger’s “ Saugethiere 
von Paraguay” in the Bulletin des Sciences Nat. 
tom. xxi. p. 469, 
VOb. IIJ. 
321 
compared with other Mammalia, prematurely 
born; and that, nevertheless, the attachment 
of the immature young to the nipple is essen¬ 
tially the same as in ordinary mammals, the 
young marsupial being nourished by the lac¬ 
teal secretion, and its blood aerated by its own 
independent respiratory actions. 
Such, therefore, being the condition of the 
problem of marsupial generation in the year 
1830, there remained to be determined by exact 
experiment and observation the period of uterine 
gestation, the structure of the fetal envelopes 
and appendages, the nature of the connection, 
if any, between the uterine fetus and the 
womb, the manner of the uterine birth, and the 
condition and. powers of the new-born young. 
With a view to the solution of these ques¬ 
tions, I applied for and obtained from the 
Council of the Zoological Society permission to 
perform the requisite experiments on the Kan¬ 
garoos in the menagerie in Regent’s Park. A 
healthy female ( Macropus major, Shaw) was 
separated from the rest ; she had a young one 
which measured about one foot two inches from 
the nose to the root of the tail, and which 
continued to return to the pouch for the purpose 
of sucking and for shelter. The right superior 
nipple was the one in use ; it was nearly two 
inches long, and one-third of an inch in dia¬ 
meter ; the mammary gland formed a large 
swelling at its base. The other three nipples 
were everted, and about half-an-inch in length. 
A healthy full-grown male was admitted into 
the paddock with this female for a certain 
period each day, and watched, during that 
time, by the keeper or myself. In the course 
of a week the female seemed to be in a con¬ 
dition to excite the sexual ardour, and after 
a few days toying on the part of the male, she 
received his embrace on the 27th August, at 
1 p.m. The female stood with her fore-paws 
off the ground, the male mounted, ( more 
canino,’ embracing her neck with his fore-paws, 
and retained his hold during a full quarter of 
an hour ; during this period the coitus was 
repeated three times, and on the second occa¬ 
sion much fluid escaped from the vulva. The 
male was removed from the female in the 
evening of the same day, and was not after¬ 
wards admitted to her. On September the 2d, 
six days after the coitus, I examined the pouch 
of the female, and this scrutiny was repeated 
every morning and evening until the birth of 
the young kangaroo had taken place. I select 
the following from the notes taken on those 
occasions ~ 
“ Sept. 6th.—10th day of gestation. The 
pouch is nearly free from its peculiar brown 
musky secretion. The right superior nipple 
retains its large size, and the young one that 
has left the pouch returns occasionally to suck. 
Sept. 11th.—15th day of gestation. Kq 
appearance of a mammary fetus ; nipples in 
the same condition ; the young kangaroo con¬ 
tinues to suck and return to the pouch fop 
shelter. 
“ Sept. 30th.-^34th day. The nipple in 
use by the young kangaroo (which has died) is 
diminished in size, and the brown secretion 
v
        

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