ment of the Kidney, and the Development of the - Journal of Cell ...

DEVELOPMENT OF AMPHIBIAN KIDNEY 455
controversy that a historical review of the subject appears to
be justified.
The classic account of the male urinogenital organs of Amphibia
is that of Bidder (1846). He first recorded that the sperm
traverses the kidney and noted the sperm-duct, lying along the
medial edge of the kidney, which to-day bears his name. Many
papers on the amphibian urinogenital system appeared during
the next thirty years, but none contributed anything to the
problem of the genital connexion except a statement by Spengel
(1876) that the ordinary excretory tubules have no connexion
with the testis. It was left to Nussbaum (1880) to start a controversy
which lasted twenty years.
This author, who appears to have been the first to study the
development of the vasa efferentia, stated categorically that
they were outgrowths from the wall of the malpighian capsule.
These outgrowths grew through the mesorchium and became
secondarily connected to an independently derived testicular
network. The ducts from the kidney were apparent in a twolegged
tadpole, but did not become attached to the testicular
network till a few months after metamorphosis. Six years later
the same author (Nussbaum, 1886) confirmed Spengel's observation,
which had been made on Eana esculenta while investigating
Eana platyrhinus [=Eana fusca]. In
the same year Hoffman (1886) entered the field with the story
that every mesonephric unit sent out a connexion to the genital
strand while this latter was still in the undifferentiated condition,
and that the posterior of these kidney-testis connexions
degenerated after metamorphosis. Unfortunately, he also stated
that the peritoneal funnels never open into veins (which can be
disproved by the examination of almost any section—cf. Gray
1930, PL 28, fig. 7), so that his description was generally discounted
on the score of faulty observation. It appears probable,
nevertheless, that the condition he described is the primitive
one in Amphibia, for it is very similar to that described by
Semon (1890) for Ichthyophis. In this animal an epithelial
strand runs out from the wall of each mesonephric duct, 'der
sich in zwei Arme gabelt; der eine tritt zur Nebenniere, der
andere zur Keimdriise. Beide sind Derivate der ursprunglichen