216 ZOOLOGICAL PHILOSOPHY 



bodies, but that when it reaches a certain degree without exceeding 

 the proper hmits, it markedly animates all the activities, is favourable 

 to reproduction and appears to expand Hfe everywhere in a wonder- 

 ful way. 



The ease, rapidity, and abundance with which, in tropical countries,, 

 nature produces and multiplies the simplest animals are facts in 

 support of this statement. The multiphcation of these animals is in 

 fact specially noticeable in favourable times and places, that is to say, 

 in hot climates and in the case of countries of high latitudes in the 

 warm season, especially when there are other conditions favourable 

 to fertility. 



Indeed at certain times and in certain climates, the earth (especially 

 at its surface where caloric always accumulates the most) and the 

 body of the waters teem with animated molecules, that is to say, 

 with animalcules of extremely varied genera and species. These 

 animalcules, like many other imperfect animals of different classes, 

 reproduce and multiply with an astonishing fertility — far greater 

 than that of larger animals with a more complex organisation. So 

 rapid are the results of this prodigious fertihty, that matter seems 

 to become everywhere animahsed. Hence, if it were not for the huge 

 immolation which overtakes the animals of the first orders of the animal 

 kingdom, they would soon overwhelm and perhaps extinguish the more 

 perfect animals of the later classes and orders of this kingdom — so 

 great is the difference between them in the capacity and ease of multi- 

 plication ! 



The above statement as regards the necessity for animals of a caloric 

 distributed throughout the environment, and varying within certain 

 limits, is entirely apphcable to plants ; but in their case heat only 

 maintains life under certain necessary conditions. 



The first and most important condition is that the roots of the plant 

 should have constant access to moisture ; for the greater the heat, 

 the more necessary does water become to the plant, to make good 

 the heavy losses of its fluids due to transpiration ; and the less the 

 heat, the less it needs moisture, which would then be injurious to 

 its preservation. 



The second condition for the elaboration of its products by a plant, 

 is that the plant in addition to heat and water should also have plenty 

 of light. ' 



The third, lastly, makes it dependent upon air, from which it pro- 

 bably appropriates oxygen and the other gases which it finds there,, 

 immediately decomposing them and making use of their principles. 



From the above statement, it is quite clear that caloric is the first 

 cause of hfe, in that it produces and maintains orgasm without which 



