DEGRADATION OF ORGANISATION 103 



If we were to imagine that such animals possess all the organs 

 known in other animals, but that these organs are dissolved throughout 

 their bodies, how absurd such a supposition would be ! 



The extremely slight cohesion between the parts of these tiny 

 gelatinous bodies is an indication that such organs cannot exist, since 

 they could not possibly carry on their functions. It is clear that in 

 order that any organs may have the power of reacting on fluids and 

 of carrying on their appropriate functions, their parts must have 

 enough cohesion and firmness to give them strength ; now this is not 

 to be imagined in the case of these fragile animalcules. It is exclu- 

 sively among the animals of this class that nature appears to carry 

 out direct or spontaneous generations, which are incessantly renewed 

 whenever conditions are favourable ; and we shall endeavour to 

 show that it is through this means that she acquired the power after 

 an enormous lapse of time to produce indirectly all the other races of 

 animals that we know. 



Justification for the belief that the infusorians or most of them owe 

 their existence exclusively to spontaneous generation is found in the 

 fact that all these fragile animals perish during the reduction of tem- 

 perature in bad seasons ; and it surely will not be suggested that such 

 delicate bodies could leave any bud sufficiently hardy to be preserved 

 and to reproduce them in warm weather. 



Infusorians are found in stagnant waters and infusions of plant 

 or animal substances, and even in the seminal fluid of the most perfect 

 animals. They are found just the same in all parts of the world, but 

 only in conditions suitable for their existence. 



Thus on examining in turn the various systems of organisation of 

 animals from the most complex to the simplest, we have seen the 

 degradation of animal organisation beginning even in the class that 

 comprises the most perfect animals and thence advancing progressively 

 from class to class, although with anomalies due to environment, 

 and finally ending with the infusorians. These last are the most 

 imperfect animals and the simplest in organisation, — the animals 

 in which the degradation that we have traced reaches its limit. 

 Animal organisation is then reduced to a simple homogeneous gela- 

 tinous body with very slight cohesion, destitute of special organs, and 

 entirely formed of a very delicate and primitive cellular tissue, which 

 appears to be vivified by subtle surrounding fluids incessantly penetrat- 

 ing it and exhahng from it. 



We have seen each special organ in turn, including even the most 

 essential, become slowly degraded till it is less special, less isolated, 

 and finally completely lost and gone, long before reaching the other 

 extremity of the order we are tracing ; and we have noticed that it is 



