THE MAMMALIA— MAN AND BEASTS. 
77 
tdrea, and Zoophytes. They seem to depend upon a certain state of the nervous 
expansion of the retina, when tlie anin.al is under the influence of rage, love, hunger, 
or any violent emotion, especially in the more furious species of Cornivora. This 
)iroperty of the retina is not pecuiiar to the Jilammalia, hut is also found among the 
Molluscu, Arnthnides, anti Crusliicta. The enormous eyes of certain Cephalopoda, 
as the Cuttle-fishes (5(7>!a), appear luminous in the middle of Uie Ocean, and ten'ify 
the Fishes, their prey. 'J'he eight eyes of the Tarantula Spider, a voracious and 
nocturnal species, arc also luminous, according to Jl. Leon Dufour. We also find 
this property among several Sauriati Reptiles, sueh as the genera Anolius and Gecko, 
whose eyes scintillate in the darkness of night, and the same assertion has heen made 
regarding the Alligators, which are thus said to frighten their prey. The ancients 
have related many fables concerning the jiiercing looks of the Basilisk Serpents, and 
modern authors have given credit to the fa.«cinating powers of the Rattlesnake. 
Certain credulous believers in Animal Magnetism have also attributed the mo.st ter- 
rific effects to the glances of the Toads, and have illustrated their credulity by 
examples. When carefully considered, these examples only prove a nervous state of 
tlie imagination when under the inlluene.e of fear. Such effects may be induced in 
sensitive frames by the approach of a hideous or dangerous object, and may be ob- 
served in the lower animals where these involuntary sensations occasion them even to 
tremble and faint- The eftect which the Painter Dog produces upon the Partridge is 
a striking instance. But the greater part of the Carnivora being nocturnal in their 
habits, such as the Cat genus, as the Lions, Lymx, Ounce ; the Dog genus, as the 
Wolves, Foxes ; the Miu-tcns, and probably also the Bats, with the Mocturnal 
Birds of Prey, have luminous eyes in the dark, whether during the night, or during 
the day, when confined in a dark chamber. Tliese animals then dilate their pupils, 
so th.at llie expanded surface of the retina at tlic back of the eye sliiiies vividly, and 
illuminates tlic external chamber of that organ. Light is thus projected i'rom witbiu 
upon those objects on which the animal fixes its gaze, that one can distinguisli them 
very well at the distance of more than a foot and a half. This emanation appears 
clearly to proceed from the exp.andcd extremity of the optic nerve. It lasts nearly 
for a minute at the pleasure of the animal, or even involuntarily when under tlie iii- 
llucnce of violent emotions. Certain Apes, a.sthe Kocthora trimrgata, and the How- 
lers (Mgeeta'), have nocturnal eyes possessed of tliLs radiating property. Inflamraa- 
lion, in various discase.s of the Eye, gives to some Men a temporary power of seeing 
in the dark, or of emitting luminous rays. The eye when rubbed, or when it 
receives a blow, becomes ilazzlcd by the sudden influx of blood into this organ, and 
not only do scintillations appear, but there is a luminous emission when these 
animals are enraged, like tliat proceeding from an electrical discharge. 
The luminosity of the retina does not proceed from a simple reflection of those 
scattered rays of Light which may ehanec to fall upon the Eye, as Treviraims and 
Jionj. Prevost have considered probable, for these phenomena can be observed in the 
most perfect darkness. The Cat, when irritated, darts forth fiery rays of liglit; its 
eyes sparkle intermittently when enraged, according to Esser and Rengger; and 
Gruithuiseu remarked that the rays acquired a greenish tinge when the animal was 
caressed. Dogs, when enraged, impart to their ocular r-idiations a tinge sometimes 
yellowish and sometimes hlueish. Their corruscations vaiy with individuals, but the 
luminous emanations appear to he most brilliant in animals with black or ash-coloured 
hair. They neither proceed from the crystalline tior vitreous humours of the Eye, 
for these can be altogetlier removed without destroying their luminous property, 
which only then acquires a more greenish hue. But on wounding the optie nerve, 
or on scraping the retina, the radiation becomes extinct ; tlms proving that it pro- 
ceeds neither from the cornea or uvea, or indeed from any of tlie transparent portions 
of the Eye. • 
GENlillAL REVIEW OR THE MAMMALIA CONTINUED. 
■Phenomena of Sleep — the llyhernation of some Species. 
The phenomena of Sleep hear an immediate relation to the most general law's of Na- 
ture, and form an important illustialioii of the fact, lhattlio periodical motions of tho 
anim.al economy are in direct currcspondcnce with the inoveinents of our planetary 
system, and especially with our situation relative to tliat Sun wliich regulates tlie pe- 
riods of the day and ye.ir. “ All our wants reappear,” says Cabanis (Rapports du 
I’hysique et du Moral de ITlommc), “and all our functions execute themselves, in 
fitted and iso-clironous periods. The duration of the functions is the same in each 
period ; the saiiic .'ippclites or the same wants have the hours marked for their retiu-n ; 
»iid it commonly happens, when these wants are not immeilialely satisfied, they dimi- 
nish and disappear for a certain time, only to return again with the greater force and 
‘mportunity at the next sueeoeding period, which ought to produce a return of the 
'niprcssion. This character of periodicity is particularly remarkable in the returns 
and duration of sleep, which commonly reappears during each astronomical day .it the 
same hour ; continues nearly for the same period of time ; and according ns it is re- 
Rular in its periods, slumber is the more easy, while the repose which follows is the 
*nore salutary ami r(‘fresUin{ 5 ^” 
'There are two principal states of vital activity, of which all animals partake in dif- 
ferent degrees. When tho vital excitement exists to its full extent, the animal is 
said to be awake ; when the functions of life arc suspondcil, citliei wholly or parlially, 
13 said to he uslcp. From this waking state, when life exists in all its plenitude, 
here may be many ilegroes of its diminution, called Uererie, Delirium, Dreamiiit/, 
Sleep, Torpor, Stupor, Asphy.via, Lethargy, according to their intensity, of which 
states the last is hut one degree removed from absolute death. 
The principal occasions on which these states of vital repose naturally present them- 
selves to our observation are, Isf, When the body and mind of an animal languish 
cither from the return of their period of natural repose, or through excessive exer- 
tion. Off, When the cold of winter, or perhaps also the heat of summer, acting on 
yecial constitutions, suspends the animal functions of life either partially or entirely, 
le former phenomenon appears daily, while the latter is of annual recurrence. 
The first of the 
Wliicl: 
so occasions, or Sleep properly so called, differs from Death, with 
1 it has often been compared, in the circumstance that all the involuntary 
20 
functions of life continue their action uninterruptedly. It may be recollected that, 
animals have two kinds of vital fuiictions ; the one vegetative and internal, which 
continue, with tho exception of gencr.ition, to exert tliemselves during the entire 
existence of each individual, and the ether purely animal, which refer to external ob- 
jects. T he former being essential to their existence, are never suspended ; the latter 
are intermittent in their action. If the heart ceased to propel the blood through tile 
arteries, if the lungs ceased to respire air, if the functions of nutrition and secretion 
were discontinued, or if they depended upon the mere Will of tho animal, life would 
soon become extinct. But all these internal actions arc involuntary, .and hence it is 
only the external and purely animal functions of life which can have their periods of 
action and repose, of waking and sleeping. These latter actions are therefore less essen- 
tial to life than the former. An animal, when profoundly asleep, is reduced to a state very 
analogous to that of a plant. Though dormant, he is still a living being, for he con- 
tinues to perform tlie functions of nutrition and secretion even more perfectly than 
svheii awake ; but he is destitute both of sensation and motion, and must awake be- 
fore he can fully resume these functions peculiar to aniuials. Thus animals have two 
states of existence, waking and .sleeping, while a plant has only one. The state of the 
latter may, however, be more or less active, according to the different degrees of heat 
or light to which it is exposed. There can ho no diiTerence with plants between the 
activity of the internal and external laiictions, and they always appear to be plunged 
in a state of repose more or less profound. Slany of the lower animals, such as an 
Oyster or a Zoophyte, when considered superficially, appear to exist in a continued 
slate of torpor, rather than to possess an active life, because they maintain but few 
relations to external objeo'.s, and hence are commonly considered rather as vegetatinu- 
than as living, although Plants .are possessed of life as well as animals, but only in 
different degrees. 
Sleep, ill fact, consists in the suspension of the organs of sense and voluntary 
motion, qualities which chiefly serve to dEtiiignish animals from plants. All the vo- 
luntary muscles rejiose completely, and the sleeping animal maintains no active rela- 
tions with external objects. The functions belonging to vegetable life continue their 
existence, hut tlie consciousness of existence is lost. The heart and the lungs con- 
tinue to act without intci ruption, wliile tlie organs of thought and sensation possess 
hut a temporary action. It is thus jirecisely tliose organs which are the most inti- 
mately comieeted with tho Mind, namely, the organs of thought and sensation, which 
most require repose, and tho human Soul, though immortal, when entirely sejiarated 
from the Body, cannot now maintain its consciousness uninterruptedly for twenty-four 
hours together. 
Night, or the absence of light, is favorable to the sleep of all animals not natu- 
rally of noeturiial habits. Silence, repose, the absence of noise, and in general every 
thing which interrupts the relations of the animal with external objects, are favorable 
to sleep. As long as the purely animal fuiictions continue to be stimulated, they 
maintain their action, until an exue,ss of action prcdmies a contrary effect. A violent 
exertion of the body, profound thought, or any powerful sensation, disposes for sleep. 
Often the fatigue of a single sense brings on the sleep of all the senses, thrmi-rh that 
intimate cuimexion maintained among all the parts of the body. The monotonous 
murmurs of a brook, the bowling of a forest, bad music, protracted reading, bad 
verses, or a lung lecture on r.n uninteresting subject, gradually fatigue the sense of 
hearing or sight, and lead the vital forces of these organs to seek in sleep for an 
accession of energy, ami the repose of the entire animal functions speedily follows. 
'1 he inclination to Sleep is amiounced by a slowness of motion, by languor of the 
Attention and Will, and by the gradual stupefaction of the senses. But tho different 
kinds of functions are suspended in a certain order of succession, according to their 
nature and relative importance. The muscles which move the arms and legs are 
relaxed and cease to act before those which sustain the bead, and the latter before those 
which support the spine. M'hcn the sense of sight is first suspended by the falling of 
the eyelids, the other senses still maintain tlicii action. The sense of Smelling is obli- 
terated before the taste ; Hearing after smelling; and Touch last of all. Even during the 
most profound sleep, the sense of touch continues to suggest ditlerent movements and 
changes of position, when tlio long duration of the same posture renders it disagreeable. 
At length animal exertion is at an end; the muscles, excepting tliose of Circulation and 
Respiration, ccasu to act; and the body sinks down, obedient to the ever-acting force 
of Gravitation. 
T hesc phenomena of Sleep are very analogous to that insensibility of particular 
organs, during our waking moments, when the .Attention is fully engaged. A pro- 
found Jlatheniatician, when absorbed in a calculation, neither sees, hears nor feels ■ 
all The functions are a.sleep except the organ of thought. Other Men, like mere 
machines moved by liahii, perform tlie same operation a thousand times with their 
hands, while the thinking jirinciplc remains buried in a profound lethargy. 
At Uie [irecisc moment when the Mind loses its consciousness, tlierc results a ge- 
neral relaxation of .all tlic muscles. If the body be at rest and m health, this sudden 
change in its state of obedience to the Will is attended with no marked result. But 
if tho liody be fatigued, or in an uneasy posture, or if the joints or muscles be pain- 
ful, this first result of Sleep has the effect of removing it entirely. Hence arises the 
lUffieulty of sleeping in a sitting posture, or during an attack of gout or rheumatism . 
Thu pain which the sudden starting of the muscles occasions is often so great in 
these diseases, that SIceji can only he induced by strung doses of opium or some 
other narcotic. It also follows from this relaxation of tho muscles, that the limbs 
become bent during Sleep, and that a substance grasped firmly in the hand, falls at 
tho instant when consciousness is lost. 
During Sleep the character of the Respiration is altered ; it becomes less frequent 
and deeper. The heart also beats more slowly, but the pulse is stronger. The 
Heat of the surrounding air, when imperfectly renewed, tends, however, to increase 
its movements. 
The heat of (ho body is not naturally higher during Sloop; on the coiki,„j, 
diminished re.spiratioii tends to lower the tempora'ure. It usually liappens. however 
from external circumstances, that tliere is an apparent rise of temperature, from tho 
body being surrounded by imperfect conductors of heat, and from the circumambient 
air being but slowly renewed. 
