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MR. H. GRAY ON THE DEVELOP31ENT OF THE 
Development of the Sup7'a-renal Glands. 
The development of the supra-renal glands being described differently by varions 
physiologists, I shall first briefly detail the researches made by others upon this 
point. 
Arnold {op. cit.) states that they are derived from the Wolffian bodies by means 
of a fissure, and that they have the same structure as these organs, a statement which 
has not, however, been confirmed by any other author. Valentin and Meckel 
believed that the supra-renal bodies exist first as a single mass, which is placed 
above and in front of the kidneys, and which afterwards divides itself into two 
lateral halves ; whilst J. Muller and Bischoff, on the contrary, state that they 
have always observed them double, although no account of their origin has been 
given by them. Mr. T. Goodsir is the only author, as far as I am aware, who has 
attempted to prove the close affinity the ductless glands (excepting the spleen) have 
to each other, by tracing out their gradual evolution in the embryo. He states that 
all of them (excepting the spleen) arise in involuted portions of the membrana inter- 
media, and that at an early period of embryonic life they communicate with one 
another. He concludes from this apparent fact, their original identity of function, 
which he says is that of elaborating a nutrient material, an office which the germinal 
membrane itself performs during fetal life. 
The description that I shall now venture to offer, differs from any that has been 
previously given of the evolution of this gland. I trust however that I may be able 
to prove the close affinity that it has both with the spleen and also with the thyroid, 
not so much from any resemblance that it may present in its manner of evolution, 
but from the similitude it presents in its elementary parts, and in the development 
of those elements to their perfect form. 
Between the sixth and seventh days of incubation, I observed that the Wolffian 
bodies had become contracted in their length, and more curved upon themselves 
than at an earlier period of their development, being somewhat reniform in shape, 
and attenuated at their upper extremities. Along the inner margin of these bodies 
was observed the ovaries, each of which consisted of a small oval mass of whitish 
blastema, occupying the central portion of each body, approximating, but not joining 
one another below, whilst they diverge from one another above. Between the 
Wolffian bodies may be observed the aorta, which bifurcates below into two lateral 
and a continuous branch. At this period the supra-renal glands, which, as will be 
seen, exist at a later period in the interval between the upper ends of the Wolffian 
bodies and the sides of the aorta, could not be observed. On the close of the seventh 
day (fig. 9), I observed in the interval between the sides of the descending aorta, and 
the upper and inner sides of the Wolffian bodies, a patchy reddish grey granular mass 
of blastema, vvithout any distinct form or outline ; whilst both the pointed but 
rounded margins of the primordial kidneys and the ovaries were plainly seen. On 
