CLASS IV. 1, 4. 1. OF ASSOCIATION. 395 



ORDO I. 



Increased .Associate Motions. 



GENUS IV. 



Catenated with External Influences. 

 SPECIES. 



1 . Vita ovi. Life of an egg. The eggs of fowls were shewn 

 by Mr. J. Hunter to resist the freezing process in their living 

 state more powerfully than when they were killed by having the 

 yolk and white shook together. Philos. Trans. It may be ask- 

 ed, does the heat during the incubation of eggs act as a stimulus 

 exciting the living principle into activity? Or does it act sim- 

 ply as a causa sine qua non, as an influence, which penetrating 

 the mass, removes the particles of it to a greater distance from 

 each other, so as to allow their movement over each other, in the 

 same manner as heat is conceived to produce the fluidity of wa- 

 ter; not by stimulus, but by its penetrating influence? Or may 

 elementary heat in its uncombined state be supposed to act only 

 as an influence necessary to life in its natural quantity; whence 

 torpor and death follow the eduction of it from the body; but 

 in its increased state above what is natural, or usual, that it acts 

 as a stimulus; which we have a sense to perceive; and which 

 excites many parts of the system into unnatural action? See 

 Class IV. 1. l.C. 



2. Vita hiemi'dormientium. The torpor of insects, and birds, 

 and quadrupeds, during the cold season, has been called sleep; 

 but I suppose it must differ very much from that state of animal 

 life, since not only all voluntary power is suspended, but sensa- 

 tion and vascular motion have ceased, and can only be restored 

 by the influence of heat. There have been related instances of 

 snails, which have recovered life and motion on being put into 

 water after having experienced many years of torpidity, or ap- 

 parent death, in the cabinets of the curious. Here the water as 

 well as the heat are required not only as a stimulus, but as a 

 causa sine qua non of fluidity and motion, and consequent life. 



3. Pullulatio arborum. The annual revivescence of the buds 

 of trees seems not only to be owing to the influence of the re- 

 turning warmth of the spring, but also to be catenated with so- 

 lar gravitation; because seeds and roots and buds, which are 

 analogous to the eggs of animals, put forth their shoots by a less 



