THE MALPIGHIAN BODIES OF THE KIDNEY. 
67 
of the tuft : it has then insinuated itself between the ball of vessels and the capsule, 
and has run off along the tube. In this case the tuft is left uninjected and contain- 
ing blood, and it becomes enveloped in a film of injection (fig. 9). Sometimes one 
side only of the tuft is injected at the moment when extravasation occurs, sometimes 
the whole, and likewise the efferent vessel (figs. 3, 4). In general, the capsule, when 
thus filled with extravasated injection, has a perfectly smooth external surface, but 
when the tuft within is also much distended, this may, in the dried and somewhat 
collapsed specimen, give to the outer surface of the capsule an uneven appearance 
like that of the tuft itself. The capsule, when distended, is seen in many instances 
to bulge and form a prominent circle round the point at which the vessels enter and 
emerge. The vessels then appear to lie in a small pit or fissure before becoming con- 
nected with the tuft (fig. 9). Lastly, it occasionally happens that though extravasa- 
tion has occurred into the capsule, the fluid has not spread itself over the whole 
surface of the tuft, and yet has passed off along the tube (figs. 3, 10, m, m). As the 
tubes in the human kidney usually become very tortuous immediately on leaving the 
Malpighian bodies, the injection running off along them may often wear the appear- 
ance of an irregular extravasated mass, and so its real nature escape observation* 
* During the course of the researches detailed in this paper, I have embraced whatever opportunities pre- 
sented themselves of studying the morbid conditions of the human kidney, and especially those usually known 
as the stages of Bright’s disease. It would obviously have been little conducive to my present purpose to 
have entered here upon a general description of the results to which my inquiries on this interesting subject 
have led me, but I cannot forbear noticing one fact of considerable importance, which will both illustrate and 
be illustrated by the preceding account of the normal anatomy of the gland. It is well known that blood is 
often passed with the urine during the course of the disease, especially at the earlier periods of it, when many 
circumstances contribute to prove that the kidneys are in a state of sanguineous turgescence. How does this 
blood escape into the ducts of the gland ? The organ examined at this time presents on its surface and through- 
out its cortical substance, scattered red dots, of somewhat irregular shape, not accurately rounded, and generally 
as large as pins’ heads, that is, very many times larger than the Malpighian bodies. These spots are very visi- 
ble on the surface, where, as I have before stated (p. 62), no Malpighian bodies exist. They have been never- 
theless described by several recent writers (not without contention for the honour of the discovery) as Mal- 
pighian bodies enlarged from congestion. How a Malpighian tuft, such as I have described it, could attain so 
prodigious a bulk, prodigious compared with its natural size, it would not be easy to explain. It is true that, 
if examined with a lens, the blood forming these spots is found to be arranged in convoluted lines, but these 
convolutions are not the dilated vessels of the tuft. They are nothing less than the convolutions of a tube filled 
with blood, that has burst into it from the gorged Malpighian tuft at its extremity. This is at once evident to 
a person familiar with the appearance of the same tubes when filled with injection in a similar manner ; and 
the figure, which I have taken from a healthy kidney so injected (fig. 11), might serve as an exact representa- 
tion of one of these spots, as seen on the surface of the diseased organ. The more or less perfect plug, thus 
often formed in the tubes, is the occasion of those dilatations of the tubes and Malpighian capsules, which are to 
be met with in the more advanced stages of the disease. Thus is to be explained the somewhat loose state- 
ment, that the disease consists essentially in enlargement of the Malpighian bodies. Though I have examined 
with great care many kidneys at all stages of the complaint, I have never seen, in any one instance, a clearly 
dilated condition of the Malpighian tuft of vessels. On the contrary, my friend, Mr. Busk, an excellent ob- 
server, has specimens which undoubtedly prove these tufts not to be dilated in the first stage, and I possess 
injected specimens showing them at all stages, but never above their natural size. I am far from implying, 
K 2 
