NOTES AND MEMORANDA. 
373 
the level of the posterior part of the glomerulus this is no longer 
the case, but here a regular series of primary Malpighian bodies 
is present, and the glomerulus of the head-kidney may fre- 
quently be seen in the same section as a Malpighian body. In 
most sections the two bodies appear quite disconnected, but in 
those sections in which the glomerulus of the Malpighian body 
comes tito view it is seen to be derived from the same formation 
as the glomerulus of the head-kidney.^' 
The point which is left in doubt in the above description, viz. 
as to whether the glomerulus constitutes a continuous structure, 
is at once decided by a study of its development. 
I may here state that it is not a continuous structure, but 
consists of a series of external glomeruli, each of which corre- 
sponds and is continuous with the glomeruli of the Malpighian 
bodies found in this part of the trunk. 
I will commence the description of the development at the 
time when the segmental tubes have reached the stage of deve- 
lopment figured by Kolliker^ and myself.^ At this stage each of 
them in the anterior region of the Wolffian body has the form of 
an S-shaped string, with a narrow opening into the body cavity, 
the lower limb of the S being formed by the intermediate cell 
mass, and the upper limb by a column of cells which connects 
the intermediate cell mass with the Wolffian duct. 
In the region where each external glomerulus is afterwards 
found the openings into the body cavity, which are homologous 
with the peritoneal openings of the segmental tubes in Elasmo- 
braiichs, widen out very considerably, and a lumen is continued 
from them into the intermediate cell mass on the one hand, and 
on the other hand into the column of cells which forms the 
upper limb of the S and connects the intermediate cell mass with 
the Wolffian duct.^ 
That part of the segmental tube which will afterwards become 
a ^Malpighian body is therefore, in the region where an external 
glomerulus will subsequently be formed, connected with the body 
* This may best be understood by examining fig. 11, PI. XVII, in my paper 
already referred to (‘ Quart. Journ. of Micr. Science,’ April, ISSO). If the 
primary Wolffian tubule here represented, were connected with the 
peritoneal epithelium at the point where the line from toL^ cuts it, and it 
were open to the body cavity at that point, an appearance similar to that 
which 1 have attempted to describe would be obtained. Or perhaps a better 
idea of the structure may be obtained from fig. G, PI. XX, in Balfour’s 
‘ Monograph on the Development of Elasinobrancli Fishes.’ If si were very 
short and wide, so that mg were widely open to the body cavity, the figure 
would resemble a developing Wolffian tubule in this anterior part of the 
chick’s Wolffian body. 
’ ‘ Entwicklungsgeschichtc dcs Menschen u. dcr hoheren Thierc,’ p. 201, 
2nd cd. 
> ‘ Quart. Journ. Mic. Sci.,’ April, 1880, PI. XVll, fig. 1. 
