NOTES AND MEMORANDA. 
On the Development of the Structure known as the ‘ Glo- 
merulus of the Head-Kidney ’ in the Chick. ^ By Adam Sedg- 
wick, B. A. — In a paper by Mr. Balfour and myself in the ^ Quart. 
Journ. of Micr. Science,' vol. xix, describing the development of 
what we believed to be a rudimentary head-kidney in the chick, 
we drew attention to a structure which so closely resembled the 
glomerulus of the head-kidney of the Icthyopsida that we iden- 
tified it as an homologous structure. 
Gasser ^ has also independently discovered and similarly iden- 
tified this structure. 
In the paper just referred to no attempt was made to trace 
the development of this glomerulus, but it was merely described 
as it appeared at its time of greatest dpelopment. 
The following description is taken from that paper : 
In the chick the glomerulus is paired and consists of a vas- 
cular outgrowth or ridge projecting into the body cavity on each 
side at the root of the mesentery. It extends from the anterior 
end of the Wolffian body to the point where the foremost open- 
ing of the head-kidney commences. We have found it at a 
period slightly earlier than that of the first development of the 
head-kidney. In the interior of this body is seen a stroma with 
numerous vascular channels and blood-corpuscles, and a vas- 
cular connection is apparently becoming established, if it is not 
so already, between the glomerulus and the aorta. The stalk 
connecting the glomerulus with the attachment of the mesentery 
varies in thickness in different sections, but we believe that the 
glomerulus is continued unbroken throughout the very consider- 
able region through which it extends. This point is, however, 
difficult to make sure of, owing to the facility with which the 
glomerulus breaks away. At the stage we are describing no 
true Malpighian bodies are present in the part of the Wolffian 
body on the same level with the anterior end of the glomerulus, 
but the Wolffian body merely consists of the Wolffian duct. At 
‘ I?cad bc-.fore the Cambridg-e Philosophical Society, 
2 ‘ Sitzungsbcrichte der Gesellschaft zur Beford d. gesain. Naturwiss./ 
No. 5, 1879. 
