misleading. Many have thought, and the 
impression still prevails, that this light 
is of a phosphorescent character, while 
others seem to think that the glow i is in- 
herent, so that the eyes of the animals 
possessing it will shine after dark or in 
an unlighted room at night regardless of 
any independent source of light. 
Both of these views are, of course, 
wholly erroneous, since the illumination 
seen in such eyes is merely the reflection 
of rays generated beyond the animal and 
visible to the observer by reflex action. 
Two disks of tin, the size of a five-cent 
piece, fastened a few inches apart on the 
trunk of a tree will so reflect the light 
from a hunter’s lantern as to deceive all 
but the most expert, and the writer has 
frequently used this method for detect- 
ing or misleading market hunters and 
others shooting at night in violation of 
law, for this destructive method is now 
prohibited in nearly all the States. 
At the present time, however, “‘jack- 
ing,” as it is usually called, has come into 
effective use in collecting scientific speci- 
mens or as an aid in the taking of flash- 
light pictures of wild life at night. Since 
most animals, big and little, are noc- 
turnal, by using a light that will cause 
their eyes to glow it 1s now possible to 
get many specimens or photograpns 
otherwise difficult to obtain and at the 
same time to use the night hours for this 
work, thus greatly increasing the oppor- 
tunities and affording more favorable 
conditions for photogr raphy. 
Originally, when hunting and later in 
night photography, the writer became 
familiar with many animals whose eyes 
glowed before a light as well as with 
those that did not have this peculiarity. 
For a long time it did not suggest any 
extended investigation, and beyond not- 
ing the different species, their actions 
under the light, and the variance in color 
reflection, nothing was done toward de- 
termining the portion of the eye that 
caused such reflection, whether it per- 
formed any function or was merely an 
arbitrary or useless attribute, without 
aie or significance in the classifica- 
tion of different families and species of 
animals. 
WHY ANIMALS CAN SEF AT NIGHT 
In considering eye reflections, they 
should not be confused with the glisten- 
77 
BUZZARD FIRING FLASHLIGHT IN DAYTIME 
The left wing became involved in string tied 
to bait and half of the pinion feathers were 
pulled out. These birds became such a nuis- 
ance that when meat bait was used the flash 
was not set until dusk. 
ing surface so characteristic of all eyes, 
human or otherwise. The exterior hght 
is mirrored on a posterior, lustrous layer 
of the retina, next to the choroid coat, 
called the Tapetum lucidum, and appears 
as a bright, luminous glow, which, in the 
case of many large animals, can be seen 
on a dark night, with a powerful lantern, 
100 yards or more away. Such glowing 
orbs have usually the brightness and 
steadiness of a star or a ball of fire, and 
can generally be detected long before the 
body of the animal becomes visible under 
the approaching light. 
While it is impossible to give here in 
detail the writer’s investigations, they 
may be summarized by stating that the 
eyes of all the carnivorous or predacious 
animals glow, as is the case with their 
domestic descendants, the cat and dog. 
The same is true of practically all the 
hoofed or grazing animals and many 
other families, while on the other hand 
the two great orders—the Primates, in- 
cluding man, apes, monkeys, etc., and the 
Rodents—have few species that possess 
the tapetum. In addition to the mam- 
