74 Mr Bles, Nephrostomial Tubules. [Feb. 10, 



paid further attention to the subject. Then, in 1886, they pub- 

 lished a paper 1 accompanied by drawings confirming, extending 

 and in one point correcting the earlier results. The figures show 

 that in Rana fusca, Rana esculenta, Bufo calamita and Alytes 

 obstetricans the nephrostomial tubules open into veins. Nussbaum 

 correctly identifies the veins as the roots of the vena cava posterior 

 and hence renal veins, not renal-portal. Figures are also given 

 showing how the nephrostomial tubules in young R. fusca larvae 

 open into the neck of the Malpighian body or into Bowman's 

 capsule just as they do in adult Urodeles, and showing a stage 

 where the tubules end blindly after losing the above connection, 

 and finally a later stage with the venous communication. In spite 

 of this, C. K. Hoffmann in the same year 2 asserts that in adult 

 Rana, Bufo and Alytes the tubules in question end blindly, but 

 confirms the communication with the neck of the Malpighian body 

 in larvae. 



In the course of researches which were carried out by the late 

 Prof. A. M. Marshall and myself 3 , we were able to confirm 

 Nussbaum's results and extend them to the English R. temporaria. 

 The adult kidney has a number of nephrostomial tubules which 

 appear to end blindly, but there are others which have distinct 

 inner openings into the renal veins. 



In this form, generally considered as identical with R. fusca, 

 the development did not follow the same course. A rod of cells 

 given off from the segmental tubule in its early solid condition 

 grows towards the peritoneum, fuses with it and acquires a lumen 

 from the peritoneum inwards. Before the lumen has reached the 

 inner end of the tubule this end loses its connection with the 

 segmental tubule and the nephrostomial tubule ends blindly. This 

 occurs in tadpoles 17 — 18 mm. long, but in 21 mm. tadpoles the 

 tubule has acquired its connection with the renal vein. 



The course of development is evidently ccenogenetic in this 

 species as compared with R. fusca, as it is in other respects in 

 comparison with R. esculenta. This divergence, therefore, cannot 

 invalidate Nussbaum's results and Hoffmann's confirmation of 

 them, and Prof. Marshall did not hesitate to incorporate the main 

 facts into his Vertebrate Embryology (p. 192). 



Nevertheless there are still many who refuse to acknowledge 

 the existence of so direct a communication between body-cavity 

 and the circulatory system, and for that reason I considered 



1 "Zur Kenntniss der Nierenorgane." Arch. f. mikr.Anat. xxvu. 1886. pp. 466- 

 9 and plate 23. 



2 "Zur Entwicklungsgeschichte der Urogeuitalorgaue bei den Anamnia." Z. W. Z. 

 Vol. xliv. p. 594. 



3 The development of the kidneys and fat-bodies in the Frog. Studies Biol. Lab. 

 Owens Coll. Vol. n. 1890. p. 133.' 



