SCIENTIFIC SUMMARY. 
435 
locally known as m’boundou, or icaja. That substance is the root of a 
plant, which is not further specified. The authors have been experimenting 
with this substance, which, even in very dilute decoctions, is very bitter, 
and appears to contain one or more alkaloids, since the aqueous decoction i3 
largely precipitated by iodide of potassium, and also by phospho-molybdic 
acid. The poisonous effects of this substance bear some similarity to the 
effects of brucia, but the authors state that, under certain conditions, this 
poison does not hurt men. Some of the lower animals are readily killed by 
it ; a dose of 3 milligrms. of the alcoholic extract, placed under the skin 
of a frog, kills it; and rabbits and dogs are killed by doses of from 15 to 25 
centigrms. of the same extract introduced into the stomach. 
Relation between White Blood Corpuscles and Pus-cells . — Very few of the 
many questions which have turned up of late years have received so much 
consideration as this one ; yet it is still unsettled. If we may j udge from a 
paper published by M. Picot in the Comptes-rendus , J une 20, it would seem 
that the idea of Conheim, that the pus-corpuscles are partly produced by 
the passage of the white blood cells through the blood vessels, is altogether 
a mistake — is a misinterpretation of the phenomena in point. M. Picot, 
whose memoir was presented by M. Robin, gave a tolerably long account of 
his observations on the circulation of frogs and mammals, and he declares 
most positively that the white blood cells never pass through the vascular 
walls, and that the pus-cells are formed gradually, external to the capil- 
laries. He explains the error of Conheim and others by stating that they 
confounded several focal planes together, and he considers that he has 
demonstrated this in the following way. He counted the number of white 
blood cells in the arrested blood in the capillaries, both before and after the 
quasi-exuded corpuscles appeared. In both instances, he says, the numbers 
were the same, and this could not have been if the white cells had passed 
outwards. We must, however, express our doubts as to the method by 
which M. Picot was so well able to count the corpuscles on both sides. 
Relation of Pigment Cells to Capillaries . — The Lancet has called attention 
to some valuable researches of Dr. Saviotti, which we should be sorry to 
omit noticing. The observer was engaged in studying the inflammatory 
process in the foot of the frog, and he first obtained a circumscribed spot 
of inflammation by means of a drop of collodion, and after a few days 
found the pigment cells of the irritated spot accumulated around the vessels 
in a contracted condition, and in the course of a short time that they had 
entirely disappeared. He immediately applied himself to the question of 
explaining the mode of their disappearance. In other frogs he excited in- 
flammation by dropping on the web a small quantity of a 2 per cent, 
solution of sulphuric acid. Again, after a few days, he saw that the pigment 
cells had accumulated around the blood-vessels, and that, though they still 
preserved their contractility, their processes were less branched and numerous 
than natural. On further examination, he now observed that these processes 
began to penetrate the walls of the adjacent capillaries and small veins, 
causing an obstruction to the onward movement of the red corpuscles on 
their proximal side, while a clear space was observable on their distal side, 
occupied only by serum. And now one of two things occurred : either the 
process of the cell broke oft’, and was swept away by the blood current, or 
f f 2 
