Se ee ae mai = eet eae» 
ei Si pean 
206 THE RADIATING ORGANS OF THE DEEP SEA FISHES. 
sally applicable, for we have found at least in one instance in Chauliodus — 
and Leydig has found the same in other instances — organs, otherwise 
identical with simple ocellar radiating ones, entirely enclosed in a pigment 
sheath and therefore unable to radiate at all. 
The diversity is in fact so great that we are forced to assume that either 
not all the organs described as radiating really emit ethereal waves, or if 
they do, that the waves emitted by different organs are either differently 
produced, or different inecharacter, or both. Although direct observations 
of the radiation of these organs are but few, we know (7) that some of them 
at least do emit light, and (2) that the light emitted by different organs is 
often different in color. 
It is remarkable that such observations have not been made more 
frequently, and that Chun who took every deep sea fish caught immediately 
to the photographic dark chamber, so often failed to observe any light 
emitted from these organs. 
On the whole [ should consider it most. probable — although very far 
from scientifically certam—that: (7) The organs produce a radiation. 
(2) In the simple ocellar organs and the radiating dises this radiation is an 
ia ethereal wave movement directly emitted into the surrounding water. 
| (3) In the compound ocellar organs this radiation is either also such a 
movement or an emission of corpuscles (electron bombardment) and origi- 
nates in the inner part. It is here not emitted directly into the surround- 
ing water, but acts on the outer part and induces this to phosphoresce and 
emit ethereal waves. (4) The length of the ethereal waves thus directly 
Hl : or indirectly produced by one and the same organ is always the same; 
that of the ethereal waves produced by different organs is often different. 
| (5) In. some cases the wave length lies within the visible part of the 
i spectrum; in other cases it may be smaller or greater, and then the radi- 
i ation is invisible. (6) The ethereal waves of the invisible radiations are 
probably of greater length than those producing the red end of the 
spectrum because such probably penetrate the water to greater distances 
and because the remarkable telescopic eyes of some deep sea animals seem 
to be peculiarly adapted to their perception. (7) These long ethereal waves 
i may (if not too long) be of the nature of (ultra red) light, or (if longer) of 
the nature of electricity. 
