QUARTERLY CHRONICLE OF MICROSCOPICAL SCIENCE, 91 
Urogenital organs.—Coincidently with the important re- 
searches of Mr. Balfour on the Elasmobranchs, published in 
this Journal, October, 1874, several observers have been 
directing their attention to the development of the Wolffian 
bodies and Miiller’s duct in these fishes. Mr. Balfour is the 
only observer who at present has published drawings of his 
discoveries. Professor Semper, of Wurzburg, has in the 
‘Centralblatt,’ July 25th, 1874, a remarkable preliminary 
note, in which he announces the discovery in the embryos of 
several Elasmobranchs (Acanthias, Centrina, Scyllium) of a 
primitive series of apertures connecting the long Urnieren- 
gang (into which they are pushed) with the peritoneal cavity. 
These are identical with the involutions first described by 
Mr. Balfour, and are, according to Professor Semper, ciliated. 
Professor Semper then in a strange way for one who has so 
strongly repudiated ‘‘ natur-philosophisch”’ speculations, 
declares that he has now furnished the proof of the genetic 
connection of Vertebrates with Annelids—the series of open 
ciliated funnels of the embryo Wolffian bodies being a series 
of “‘ segmental organs,” one corresponding to each metamer 
or somite of this region of the vertebrate’s body. Professor 
Semper is not the first by any means who has seen that the 
genetic affinities of the Vertebrata are with an annelid-like 
invertebrate, nor is he the first who has clearly seen the 
relationship of segmental organs and the primordial verte- 
brate kidney.!. Whatever modification of his earlier views 
may be necessary, it is to Professor Gegenbaur that the 
merit of this as of so many other fruitful suggestions is due 
(see his ‘ Grundzuge der Vergleich Anat.’). The discovery 
of this series of ciliated funnels makes it probable that the 
unsegmented character of the primordial kidney of Bdello- 
stoma is due to the fusion of a series of distinct segmental 
organs, and not to the persistence of an unsegmented struc- 
ture (like the notochord) from an unsegmented ancestral 
form. In his zeal to crush the teaching of the Jena school, 
Professor Semper declares that the Mullerian duct (Urnie- 
rengang), with the sides of which the Wolffian bodies with 
their funnel-like mouths appear primitively to have been 
connected, has nothing to do with the said Wolffian seg- 
mental organs. The comparison of the primordial kidney of 
Bdellostoma with the various conditions of these organs in 
2 Dr. Anton Dohrn, of the Zoological Station, Naples, has for some years 
been engaged in elaborating a theory of the “ Annelidan Origin of the Ver- 
tebrata.” The evidence in favour of such a view, which he has collected, 
is very much more extensive than that adduced by Professor Semper. A 
memoir on the subject, by Dr. Dohrn, will be published in January. 
