118 REPORT—1868. 
These may be briefly summarized thus :— : 
(1) The odontoid process is the body of the atlas ; a considerable amount of evi- 
dence on this point is contained in the original paper. 
(2) The preodontoid half-arch of the atlas is considered by Koster as a heemal 
arch, by Owen as a hypapophysis; but in the author’s paper reasons are given 
for considering it as an ossified anterior conjugal ligament, like the middle slip of 
the stellate thoracic ligament. 
(3) The transverse ligament of the check-ligaments are serial with the con- 
jugal ligament of the ribs. 4 ; 
(4) The third occipital condyle is homologous with the central part of the orni- 
thic and reptilian condyle. 
And lastly, the articular surfaces of the atlas and occipital bone are structurally 
double, the anterior part being in series with Luschka’s Halswirbel, the posterior 
part being probably related to the true oblique process. 
On the Transmission of Light through Animal Bodies. 
By Dr. Ricuarnson, M.A., FBS. 
The author exhibited a lamp which he had constructed for transmitting light 
through the structures of the animal body. He believed the first idea that such 
transmission could be effected was given in Priestley’s work on Electricity. That 
great experimentalist, the Shakspeare of physical science, had observed, on passing 
a discharge of a Leyden battery through his finger, that the structure seemed to 
present Juminosity, but the operation was extremely painful. The author had 
repeated this experiment with similar results. Of late years research had been 
made with the microscope in the transparent web of the foot of the frog; and 
last year Dr. M‘Intosh had shown that young trout could be used experimentally, 
they being sufficiently transparent for the investigation of the action of various 
oisonous substances on their internal organs. The suggestion of Dr. M‘Intosh 
had been acted upon by the author, and the motion of the heart and of the re- 
spiration had been observed by direct ocular demonstration while those organs were 
under the influences of various bodies belonging to the ethyl and methyl series. This 
research had led the author to extend the principle further ; and he had now ad- 
vanced so far that he was enabled to transmit light through various tissues of the 
bodies of large animals. He had thought it was best to begin by testing each 
tissue separately; and this investigation had been carried out on nearly all the 
structures of the body which admit of being individually examined. The structure 
the most diaphanous was the skin; after that, and singularly enough, bone; then 
thick membranes; next, thin superficial muscles, lung tissue, fat, and the dense 
tissues of the liver and the kidney. Various lights had been tried, viz. the 
electric, the oxyhydrogen, the lime-light, and the magnesium. For all practical 
purposes, the magnesium light was the best: it was the most convenient to use, 
and the light had the advantage of penetrating deeply. In the lantern which the 
author exhibited the light was also unattended with heat at the poimt of observa- 
tion, so that the hand could be put in at the brightest illuminating point. The 
lamp was made by Solomon, of Red Lion Square. The additions consisted in a 
tubular arrangement and asliding groove. The structure to be examined was placed 
in the groove inclosed between two disks of perforated wood, and the object was 
surveyed from the further end of the tube. In illustration, a thick piece of bone 
(the flat rib of an ox) was placed in the lantern, and light was distinctly trans- 
mitted through it. “It was,’ said the author, “important to speak with care as 
to the extent to which this lantern could be used practically.” He did not con- 
sider it perfect, but thought it promised results of the greatest interest and value. 
In the first place, it might be used for a variety of physiological purposes. Animals 
whose tissues were thin, such as fish, could be placed in the lantern, and the con- 
dition of their circulation and respiration could be carefully studied under the 
action of various agents. In the human subject, especially in the young, having 
fragile tissues, the thinner parts of the body could be distinctly rendered: trans- 
parent ; and in a child the bones, under a somewhat subdued light, could be seen 
