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

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456 PETER GRAY Verbindung zwischen Nephrotom und Seitenplatten und zwar des inneren Theils dieser Verbindung.' These later degenerate in those segments in which sex-cells are not produced. In 1897 Prankl investigated the sperm-passage by injections made through the archinephric duct. He stated in contradiction to Nussbaum (loc. cit.) that the sperm passed through special ducts, but admitted that these were clearly connected with normal malpighian capsules in which both sperm and injection mass were to be found mixed. The rapid exchange of' Aufsatze', 'Bemerkung iiber Aufsatze', &c, which followed between the two authors is not here cited, as it contributed nothing to the solution of the problem, ultimate agreement being reached that the difference in their results was a natural difference between Eana fusca and Bana esculenta. This controversy led Beissner (1898) to investigate the kidneys of Eana esculenta and Eana fusca. He wrote a very short paper, nearly half of which is historical summary. This paper is illustrated with two admirable diagrams which showed that the differences between Prankl and Nussbaum could be reconciled if it were postulated that Eana esculenta had both a dorsal and a ventral transverse sperm-canal, while Eana fusca had only a dorsal one; if this were so, then sperm would have not only special canals (Frankl on Eana fusca) but they would pass through normal units (Nussbaum on E a n a esculenta) in order to reach the second transverse canal of this latter form. As both his title and text show he never intended to do more than reconcile the two outstanding opinions. Gaupp (1904), who was then preparing the new edition of Ecker's und Weidersheim's ' Anatomie des Prosches', republished both of Beissner's diagrams and accepted his postulate of a second transverse canal as an observed fact. The diagrams have since been widely published in text-books, and thus has arisen our present conception of the sperm-passage in Eana. Beissner's theoretical diagrams have even (Stewart 1927) been accepted as wax-reconstructions. With Gaupp's publication (loc. cit.) the matter was taken as finally settled, if we except a brief statement by Gerhartz (1905) that Nussbaum's view was correct.
DEVELOPMENT OF AMPHIBIAN KIDNEY 457 Interest arose again when the 'germ-track' controversy produced a spate of papers on the development of various gonads. In the course of a study of the development of the sex-cells of R a n a, Kuschakewitsch (1910) makes some mention of the vasa efferentia. He considers that they arise from the testis-stroma at a time when this is still confused with the kidney blastema. Witschi (1913) gives an excellent account of the development of the collecting ducts within the testis and points out that these groAv out from the central strand of stroma; they acquire a secondary connexion with the extra-testicular portion of the duct system. Swingle (1925) also discussed the development of the testis, but in referring to the development of the vasa efferentia he stated that everything was already known about it. He quoted Kuschakewitsch and Witschi (loc. cit.), attributing to the former the statement that tubules originating from the kidney end blindly before reaching the testis; I cannot find this stated in Kuschakewitsch (1910). Swingle's most remarkable suggestion, however, is that the indifferent gonad is induced into a testis by the arrival of the growing vasa efferentia; it is a little difficult to imagine what starts the vasa efferentia growing, or stops them growing and permits a female to be produced. Van Oordt (1922) in the course of completing Witschi's work on testis development, examined. the genital connexion in some post-metamorphic Bana fusca; in a few examples he found ducts which originated from the kidney but did not reach the testis and also records the appearance of some unconnected ducts in the fat-bodies. It is noteworthy that none of these investigators of the gonad traced the vasa efferentia into the kidney and none therefore can offer any suggestion as to the origin of the outgrowths which they presume. The most recent contribution to the problem is that of Lloyd (1928), who points out that modern text-books of zoology state that the sperm passes through ordinary kidney-ducts, and says that he has examined many hundreds of sections without finding a sperm-duct. The work is cited here only as proof of the concensus of modern opinion.
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