400 ULRIC D3, HLGREX. [J. F. I.

The whole three organs show their light simultaneously upon ally decided stinmlation. This is difficult to observe, because one has to injure the animal seriously in order to expose the six organs to the eye. When opened, however, an hour or less of rest in salt water or in a moist chain,her at the natural temperature of the sea from which the organisms were taken will reduce the luminous organs to quiescence, and one can then perform stimulation ex- perimnents and study the light.

F6rster made a careful study of the nerves that come to the luminous tissues and found all the light organs to be well supplied with large stems that branched out and sent their fine twigs into the tissue of the organ. The exact termination of these nerves, however, was not described: whether each cell of the two layers was provided with a means of being stinmlated to discharge its contents, or whether the cells did not connect with the nerve, but the latter ended on mnuscle-fibres which could contract and squeeze the entire organ so as to press out the secretion. While both of these methods seem possible, the writer thinks that each cell is probably provided with a nerve-ending to enable it to discharge when the general signal is sent out from the central ganglion. I f some investigator would open a Pholas, cut the nerve-trunks on one side, and then experiment with both mechanical pressures and stimulations of the nerve ganglia, this question ought to be easily solved.

The color of the light in Pholas is ordinarily greenish or greenish-blue as seen in the majority of luminous animals.

(To be continued.)

Incandescent Electric Headlight Equipment. ANON. (Rail. way Age Gazette, vol. 66, No. 7, February I8, I916.)--During the past few years the Sehroeder Headlight Company, of Evansville, Ind., has given much attention to the development of incandescent electric headlight equipment to meet the growing demand for head- lights of this type. At the present time it has on the market three types of equipment, namely, the 6-volt turbo-generator, having a capacity of 15o watts, and two 32-volt generators having capacities of 35 ° watts and IOOO watts respectively. The 32-volt, 350 watt system has been the most extensively used up to the present time, and has already been made standard on some roads. According to the report of a road operating in the middle West, the average cost of operation is $I 1.54 per machine per year.