SPONTANEOUS GENERATION 245 



Now light is known to generate heat, and heat has been justly 

 regarded as the mother of all generations. These two distribute over 

 our earth at least, the principle of organisation and feeling ; and since 

 feehng in its turn gives rise to thought as a result of the numerous 

 impressions made on its organ by external and internal objects through 

 the medium of the senses, the origin of every animal faculty may be 

 traced to these foundations. 



This being the case, can it be doubted that heat, that mother of 

 generations, that material soul of living bodies, has been the chief 

 means employed directly by nature for working in appropriate material 

 the rudiments of organisation, a harmonious arrangement of parts, 

 in short, an act of vitaUsation analogous to sexual fertihsation ? 



Not only has the direct formation of the simplest living bodies 

 actually occurred, as I am about to show, but the following principles 

 proves that such formations must still be constantly carried out and 

 repeated where the conditions are favourable, in order that the existing 

 state of things may continue. 



I have already shown that the animals of the earliest classes (in- 

 fusorians, polyps, and radiarians) do not multiply by sexual repro- 

 duction, that they have no special reproductive organ, that fertihsation 

 does not occur in them and that consequently they lay no eggs. 



Now if we consider the most imperfect of these animals, such as 

 the infusorians, we shall see that in a hard season they all perish, or at 

 least those of the most primitive orders. Now seeing how ephemeral 

 these animalcules are, and how fragile their existence, from what 

 or in what way do they regenerate in the season when we again see 

 them ? Must we not think that these simple organisms, these rudiments 

 of animality, so dehcate and fragile, have been newly and directly 

 fashioned by nature rather than have regenerated themselves ? This 

 is a question at which we necessarily arrive, with regard to these singular 

 creatures. 



It cannot then be doubted that suitable portions of inorganic matter, 

 occurring amidst favourable surroundings, may by the influence of 

 nature's agents, of which heat and moisture are the chief, receive an 

 arrangement of their parts that foreshadows cellular organisation, 

 and thereafter pass to the simplest organic state and manifest the 

 earhest movements of Hfe. 



If it is true that unorganised and hfeless substances, whatever they 

 may be, could never by any concurrence of circumstances form directly 

 an insect, fish, bird, etc., or any other animal which has already a 

 complex and developed organisation ; such animals certainly can only 

 derive their existence through the medium of reproduction, so that no 

 fact of animalisation can concern them. 



