44.0 ADAM SEDGWICK. 
intermediate cell mass with the commencing lumen from the body 
cavity. 
‘ah the next section the intermediate cell mass is not 
connected to the peritoneal epithelium. 
In chicks of gradually increasing number of protovertebre this 
cavity in the intermediate cell mass gradually becomes more 
marked (figs. 13, 14), and extends into that part of it imme- 
diately behind the peritoneal connection (fig. 15). 
Figs. 13, 14, and 15 are three successive sections through the 
13th segment of a chick with about thirty segments, showing 
the features of a tubule at this stage. 
The Wolffian duct is connected with the lower end of the in- 
termediate cell mass in all the three sections. A distinct lumen 
has appeared in the intermediate cell mass which opens into the 
body cavity in front (figs. 13 and 14), but is separate from the 
body cavity in the hindermost section (fig. 15). 
Comparing these figures with figs. 9 and 10 it is seen that 
fig. 18 or 14 corresponds to fig. 9 in the fact of the continuity 
between the intermediate cell mass and peritoneal epithelium ; 
while fig. 15 corresponds to fig. 10, in both the continuity 
having been lost. The difference between them consists in the 
presence of a distinct lumen in the older series, opening into 
the body cavity, and continued behind into the part of the 
intermediate cell mass which has separated from the peritoneal 
epithelium. This part, marked 2. ¢. m. in fig. 15, will in the 
next stage become converted into that part of the tubule in 
which a Malpighian body is developed, while the anterior part, 
which is open to the body cavity, will widen out considerably, 
and give rise to a wide peritoneal funnel, 
In fig. 11 is represented a section through a developing 
Wolffian tubule in the hinder part of the Wolffian body. The 
tubule (w. Zé.) in this section precisely resembles the part of the 
tubule (2. c. m.) represented in fig. 15. Supposing the anterior 
part of w. ¢1. were open to the body cavity it would almost be a 
repetition of the anterior tubule, save in the fact that it is not yet 
united to the Wolffian duct. But the hinder tubule (fig. 11) 
does not develop until after the intermediate cell mass has sepa- 
rated from the peritoneal epithelium, 7. e. subsequent to the 
obliteration of the rudiment of the peritoneal funnel. 
Not only do the Wolffian tubules in the region of the 12th 
to 15th segments develop a lumen while still continuous with the 
peritoneal epithelium, but further, a glomerulus appears in them 
while still open to the body cavity; and this glomerulus not 
only appears in the hinder part of the tubule (fig. 15) which 
has separated from the peritoneal epithelium, but also in the 
anterior part (figs. 13 and 14) where it is open to the body 
