KIDNEY IN RELATION TO WOLFFIAN BODY IN THE CHICK. 155 
Wolffian tubules is not easy to answer. I leave it open now, 
but hope to be in a position to give a definite answer soon. 
Now I will merely state that there are appearances in my 
sections which incline me to the opinion that there are out- 
growths from the Wolffian duct which, in the case of the 
primary Wolffian tubule, are solid, but hollow in the case of 
the secondary and tertiary tubules. 
The above description of the development of the primary 
Wolffian tubules difiers from the most recent account of 
Kdlliker^ and Fiirbringer.^ I have stated above the views 
which these distinguished observers hold as to the develop- 
ment. They have described perfectly correctly one stage in 
the development of the anterior part of the Wolffian body. 
I have often seen the appearances given by Kolliker in fig. 
l2o of his work, and have given myself a similar represen- 
tation (fig. 1). But if I understand them correctly they 
have given an erroneous account of. the earlier development 
of these structures. Fiirbringer says of them (p. 67) : “ Sie 
finden sich in reihenweiser Anordnung als solide Urnieren- 
strange die von dem parietalen Peritoneum ventral und 
medial vomWolff’schen Gange ausgehen. . . . Sehr bald losen 
sich diese Urnierenstrange von dem parietalen Peritoneum 
ab undliegennun als rundliche solide Zellenmassen retrope- 
ritoneal neben dem Wolffischen Gange, ein Stadium das die 
Beobachtungen der mersten Autoren deckt.” It is easy to 
see how Fiirbringer has been misled. He has seen in trans- 
verse sections in a fairly young chick the S-shaped strings 
of cells (solide Urnierenstrange) in connection with the peri- 
toneal epithelium. He has also seen in an older chick the 
Wolffian blastema of the posterior region of the Wolffian 
body (rundliche solide Zellenmassen). Both these observa- 
tions I can entirely confirm. But apparently he has not 
examined the condition of these structures at an earlier 
stage, assuming that they originate as solid outgrowths of 
the peritoneal epithelium. This assumption my observa- 
tions prove to be unwarranted. 
The older observers (see above) were quite correct in their 
statements of the origin of the Wolffian tubules, as struc- 
tures developed in the intermediate cell mass, independently 
of the Wolffian duct, and later acquiring an opening into it, 
AValdeyer’s^ statement that the Malpighian body thus 
develops, the rest of the Wolffian tubule developing as out- 
growths from the Wolffian duct, is in my opinion erroneous. 
For if there be an outgrowth from the Wolffian duct it 
does not give rise to the whole tubule, exclusive of the 
* hoc. cit. 2 ‘ Morpli. Jabrbucb,’ B<1, 4, ’ Loc. cit. 
