KIDNEY IN RELATION TO VYOLFIAN BODY' IN THE CHICK. 149 
Kupfter,^ Bornhaupt/ and Braun/ on the other hand^ 
assert that the secretory tubules and Malpighian bodies are 
formed independently of the ureter in the condensed meso- 
blast tissue mentioned above^ the outgrowths from the ureter 
merely giving rise to the collecting tubules. 
I shall return, when I have described the kidney develop- 
ment in the chick, to a consideration and discussion of 
the various hypotheses which have been held concerning the 
Amniote kidney. 
Development of Wolffian body , — The ages of the younger 
embryos from Avhich the sections figured in the accompany- 
ing plates (XVII and XVIII) were taken are indicated by 
the number of protovertebrse. In the older embryos this 
was not possible. In most cases the place in the body, 
from which a section figured was taken, is indicated by the 
number of the segment^ in which it occurred, counting 
the first segment behind the auditory involutions as the 
first. 
These determinations have been made with some care by 
mounting all the sections in order, and then by observing the 
protovertebrse, arranging them into groups corresponding to 
each protovertebra, beginning the process always in front. 
The observations here recorded do not extend to any part 
of the Wolffian body in front of the fourteenth segment, nor 
to the development of the Wolffian duct. I have made 
some observations on both these parts, but they are not yet 
sufficiently complete to enable me to understand certain 
remarkable appearances in their development. The Wolf- 
fian body, like most other organs, develops first of all in 
front and then gradually backwards, so that supposing the 
development behind were the same as in front, the process 
might be shewn by a series of sections from a single chick 
of the proper age. But this is not the case. In the chick 
the development of the Wolffian tubules behind is very 
different to that in front. This fact has apparently been 
overlooked by the most recent observers. 
The development of the Wolffian body in the duck is 
much more completely similar throughout than in the chick, 
and reference will be at first made to figs. ^ — 5, taken from 
a duck embryo with thirty-one or thirty-two proto vertebra 3 , 
in the following description. 
^ ‘ Arch. f. Mic. Anat.,’ Bd. 1. 
‘ Untersuchungen iiber d. Entwick. des Urogen. systems beiin 
liuhncben,’ Diss. Inaug., liiga, 1867. 
^ Loc. cit. 
^ The term segment is used as equivalent to protovertebra, muscle 
plate. 
