Short Papers and Notes. 29 
we must abstain from self-assertion, and throw upon our accom- 
plishments and talents the delicate veil of modesty. 
Production upon Wood of Photographic Proots 
destined for Engraving. 
The block of wood is first covered with a layer of gelatine 
(0°39 grms. to 0.31 grms. of water) by means of a soft brush. 
When this coating is dry, it is covered, in the dark, with a solution 
prepared of (1) red prussiate of potash, 7°80 grms., and water, 
62°20 grms. ; (2) ammonia-citrate of iron, g'10 grms., in 62°20 
grms. water. These solutions are mixed and filtered, and the 
mixture is kept in the dark. When the layer is dry, it is exposed 
under a negative for from ten to twelve minutes, and washed with 
a soft sponge, when a blue tinge appears. If thus prepared, the 
coating does not peel off under the graver. V. A, LATHAM. 
The Duminous Organs of Fnsects. 
Dr. Dubois has investigated the light-emitting organs of the 
Cucuyo or Pyrophorus noctilucus. They are three in number—two 
prothoracic and one ventral. The prothoracic plates give a good 
illumination in front, laterally, and above, and serve when the 
insect walks in the dark; when it flies or swims, its fine abdo- 
minal lantern is unmasked, throwing downwards an intense light 
with much greater range. The insect seems to be guided by its 
own light. If the prothoracic apparatus is quenched on one side 
with a little black wad, the Cucuyo walks in a curve, turning 
toward the side of the light. If both sides are quenched, it walks 
hesitatingly and irregularly, feeling the ground with its antennze 
and soon stops. 
The light gives a pretty long spectrum from the red to the 
first blue rays, is more green than the light of Lampyris noctiluca, 
and is incapable of photography, but does not develop chloro- 
phyll. No distinct electric action could be traced to the organs. 
The luminosity does not depend upon oxygen in air, in pressure 
under one atmosphere, and in compound oxygen. The organs 
are still brilliant when separated from the body, but the power of 
emission appears to depend upon a supply of water, and it is 
recoverable, after thorough drying, upon putting the organs again 
in water. Dr. Dubois found that the photogenic substance is an 
albuminoid, soluble in water, and coagulable with heat, it entering 
into contact with another substance of the diastase group. Part 
of the energy liberated appears as light. 
Al Reasoning Lobster. 
While at Bird Island, Buzzard’s Bay, Mass., I noticed what 
Wo, 1000 2—2 
