The Cambridge natural history, Vol. 08 (of 10)Gadow, Hans
Science
The Cambridge natural history, Vol. 08 (of 10)
Gadow, Hans
Animals
Schwalbe also explains the whole question of the reduction of the number of
embryos. He says rightly that in _S. maculosa_, which gives birth to many
young, there are in the oviduct many eggs which have only partly developed
into embryos, and these, perhaps from want of room and nourishment,
degenerate into the irregularly shaped whitish-yellow bodies which are
occasionally found packed in between the developing embryos. Consequently
all those eggs had been fertilised near the ovaries. _S. atra_ exhibits a
further stage in so far as most of the eggs, fertilised above in the
oviduct, degenerate, and only two or three become fully developed. These
few embryos live on the degenerating eggs, which together produce the
vitelline material spoken of above. The two full-grown and metamorphosed
embryos, each measuring about 50 mm. in length, are equivalent to the
numerous new-born larvae of _S. maculosa_, especially if the smaller size
of the adult Alpine Salamander is taken into consideration.
Mlle. von Chauvin[59] has experimented with the unborn larvae of this
Salamander. She cut out 23 larvae and put them into water. One of them,
already 43 mm. long, took earthworms on the next day, and the beautiful
long, red gills became pale and shrunk, and on the third day were cast off
close to the {121}body. New gills sprouted out on the same day, first in
the shape of three tiny knobs on either side. After three weeks they had
become round globes, which gradually sprouted out into several branches,
far shorter and more clumsy than the original gills. During the whole time
the larva was lying quietly at the bottom, in the darkest corner, but
showed a good appetite. The fin of the tail disappeared and was supplanted
by a stronger one. In the sixth week the skin was shed in flakes, and this
process took fifteen days. This larva lived in the water for fourteen weeks
and grew to 6 cm. in length! When the new gills gradually shrank, the
compressed and finny tail assumed a round shape, the skin became darker and
shinier, and after the larva had again shed its skin, there appeared the
dark rugose skin of the typical _S. atra_. The gills were reduced to
useless appendages–not cast off–and the creature crawled out of the water.
A fortnight later the gill-clefts were closed. A second larva behaved
similarly, first casting off the feathery gills, substituting a new and
stronger set, which, however, fourteen days after excision from the uterus,
shrank again, and on the nineteenth day the gill-clefts were closed. The
lady also observed that nearly ripe larvae, when cut out, rushed about in
the water and ate, just like the new-born larvae of the Spotted Salamander.
Public-domain text, read in full here on John Shaqi.
Reviews
Reviews
No reviews yet
Be the first to share your thoughts on this work.
Elsewhere in the archive
Join the Discussion
Join the discussion
Sign in to leave a comment or review.
Sign InorCreate an account