422 Scientific Intelligence. -—Comparative Anatomy. 
appear on different parts of the body, and sometimes like waves, 
that move across its surface with the velocity of an arrow. This 
phenomenon is caused by the rapid and simultaneous contraction 
which takes place in all the vesicles of a particular part of the 
bod}, and from the sudden and simultaneous expansion of all 
the vesicles on another part. This appearance continues until 
the whole body of the animal is covered with it, and its natural 
colour is changed for that of the vesicles. 3. If the animal re- 
mains long in this state it dies ; but if it is again returned to its 
proper element, and we cease to irritate it, then it begins to com- 
pose itself, considering danger as ovei, when the vesicles become 
smaller and smaller; and when they entirely disappear, the skin 
assumes its natural colour. From the preceding observations, 
the following results are obtained: — }. Each of these colour- 
ed vesicles, in their expanded state, assumes the oval or round 
shape ; internally they are empty, and resemble the husk of a 
grape. 2. Each of these vesicles is composed of a skin, having 
the structure of felt, is very irritable, and, on account of its 
structure, is necessarily capable of expansion and contraction. 
3. The motion of systole and diastole, in these vesicles, can be 
produced by a very slight irritation, even long after the death of 
the animal. 4. These vesicles are provided with a circular aper- 
ture, which can open and shut, probably by means of a circular 
muscle, and which enables us to see to the bottom. 5. The ex- 
pansive and contractive power with which they are provided, du- 
ring life, is owing to their particular structure, which is subjected 
to the influence of the general nervous system, with which they 
are connected by means of delicate nerves ; for every motion in 
them ceases when the skin is separated from the body. 6. The 
pow T er which the vesicles possess, of moving, after the death of 
the animal, depends on a remaining portion of excitability. 7. 
These vesicles, in the dead animal, are sensible to the action of 
stimuli, and are quick in their motions ; in the living state they 
are very irritable, because their contraction and expansion take 
place with extraordinary rapidity. 8. The motions of these or- 
gans are voluntary during life, but passive after death. 9. The 
vesicles are subject, not only to a particular individual motion, 
but also to a general motion, w hich is undulatory, and is peculiar 
to the dermoidal system. 10. This dermoidal organ, which con- 
sists of different orders of microscopic empty vesicles, distinguish- 
