received from the Society for the last five years during which investigations on Electric Radiation have been in progress at the Presidency College. I may say that the difficulties have been very numerous and disheartening, and that without this encouragement the work which it has been my good fortune to carry out would in all probability have remained unaccomplished. The Government of Bengal has also been pleased to evince a generous interest in these investigations. My assistant, Mr. Jagadindu Ray, and my pupils, Messrs. P. K. Sen, B.A., and B. C. Sen, B.A., have rendered me active assistance.]
(Abstract.)
Observations were made on the eye of the living animal, 181 different species being examined, and frequently several individuals of the same species. The species comprise representatives of all the Mammalian orders except the Cetacea and Sirenia.
The conclusions arrived at can be summed up as follows:—
The colour of the Fundus oculi in animals devoid of a Tapetum is mainly determined by reflection from the choroidal pigment; in those with a Tapetum cellulosum (Carnivores) by the colour of the retinal pigment; in those with a Tapetum fibrosum (Ungulates) by the structural colour of the Tapetum modified by the colour of the retinal pigment. All the animals examined may be classed under three types—red, yellow, and green.
The vascularisation of the retina can be summarised as follows:—
1. Indirect supply by means of osmosis from the vessels of neighbouring parts. A. Hyaloid supply. (a) The corpus vitreum is nourished by a processus falciformis, the hyaloid vessels lying well inside the corpus vitreum (Elasmobranchs). (b) The hyaloid vessels spread over the surface of the corpus vitreum, being in consequence in the immediate vicinity of the retina (e.g., holosteus and many teleosteous fishes). Hereto belong also the Amphibia and most of the Reptiles devoid of a pecten. B. Choroidal supply. This is probably the chief supply of the retina in those animals which possess a well-developed pecten (most Sauropsida), but are devoid of superficial hyaloid vessels. This choroidal supply by osmosis is also with certainty demonstrated in the Mammalia for at least part of the thickness of the retina.
2. Direct supply. A. From the superficial hyaloid vessels. This is
