10 
rROCEEDINGS OF THE ACADEMY OF 
[Biolog. 
Dr. Mitchell mentioned, that he had found the "greatest facility in obtain- 
ing hnman blood-crystals from pneumonic clots. 
Dr. Morris expressed the opinion that blood-crystallization is a result of 
change in the albuminoid matter of the corpuscles, under the action of oxygen ; 
the crystals being seldom formed without exposure to the air, or, at least, with- 
out time for partial cadaveric decomposition. They are, therefore, derivative 
in their nature. 
Leaving this subject, — Dr. Morris stated, that he had been interested, while 
observing some plants in bloom near a closed window, in finding a deposit of 
moisture upon the glass, immediately opposite to each flower; there being 
none opposite to the leaves. This was not what he should have been led to 
expect, from the recognized action of the leaves, in concentrating the sap of 
plants by evaporation. Opposite to the flowers of a Camellia, there had also 
been found a collection of a viscid sweet substance. 
Dr. Leidy supposed this sweet substance to be the secretion ejected by an 
aphis, which sucks the juices of flowers, and throws out continually what is 
called, as it appears on many plants, honey-dew ; which constitutes the value 
of the aphides to ants, whence they have been called ant-cows. On grape- 
vines, in summer, the black aphides abound, and black ants may be seen 
running up and down, eating this substance, thrown out when the aphis is 
irritated. It has the power of ejecting it to a considerable distance. On 
the flowers and other parts of the Ailanthus and Tulip-poplar, drops of it, 
darkened by dust, are often visible ; the Camellia is especially well adapted 
for their display. 
Mr. E. TiLGHMAN exhibited and explained briefly his application of photogra- 
phy to the construction of goniometers and micrometers. It consists, essentially, 
in taking by a microscopic camera a photograph on glass of a graduated semi- 
circle, of proper size to place on the diaphragm of an ordinary Huygheman 
eye-piece, so as, by super-position, to measure the angle of microscopic crys- 
tals. The base of the graduated semicircle may also be divided as a micro- 
meter, so that the same instrument may be used for the two purposes. By 
advancing or withdrawing the microscopic camera to or from the negative, put 
up against the light, the graduated semicircle may be adapted to any sized eye- 
piece. The cost of this construction is very small. Mr. Tilghman anticipates 
making a fuller report upon the subject at some future time. 
Dr. Leidy exhibited a number of sections of the human cranium, illustrating 
the beautiful mechanism by which union of the dififerent parts of the skull is 
effected, not only in man, but throughout the whole animal kingdom ; and 
which is especially striking before the sutures are co-ossified. One section 
was horizontal, one vertical antero-posteriorly, and four vertical laterally. In 
all, minute examination displayed the most exquisite overlapping and inter- 
junction of parts, completing that adaptation to its contents, which is obvious in 
the form and whole construction of the cranium. 
April 12th. Dr. J. Darby read an elaborate paper on the Supra- Renal Cap- 
sules; advancing the opinion, based on original observation and research, that 
those organs are so important to the normal condition of the blood, and to the 
functional actions of the nervous system, as to be almost indispensable to life. 
Dr. W. A. Hammond read a description of a Case of Fatty Degeneration of the 
Heart, in which death followed the inhalation of chloroform. The impurity of the 
chloroform (or chloric ether) used in this case was such, that Dr. Hammond 
supposed it possible that this might aid in accounting for the fatal result. 
Dr. H. Hartshorne, in connection with the same subject, gave an account of 
some experiments made by himself with the inhalation of deodorized alcohol. 
An inhaling apparatus on the ordinary principle was used, air being introduced 
only through the alcohol. After breathing through the tube of the apparatus 
for ten minutes, a feeling of exhilaration was produced, without somnolence or 
circulatory excitement, but with some diminution of sensibility ; and, in one 
instance, with forcible, though not accelerated palpitation of the heart. The 
[April, 
