294 THE PHILOSOPHY OF BIOLOGY 



a priori verifiable, is found. What, for instance, are 

 our mathematical methods of integrating a function, 

 or working a long division sum, but methods of scien- 

 tific " guessing," and verification of the hypotheses 

 so made ? They are truly instances of the method of 

 trial and error practised by the lower animals. 



All the above amounts to saying that there is a 

 community of energetic processes, of morphology, and 

 of behaviour in animals and plants. " Protoplasm " 

 is the same, or much the same chemical aggregate, 

 whether it is contained in the cells of animals or plants. 

 The cell, with its nucleus, chromatic architecture, cell- 

 inclusions, and cell-wall, is essentially the same structure 

 in all organisms. The complex and specialised process 

 of nuclear division in tissue growth, or the series of 

 events which constitute the acts of fertilisation of the 

 ovum or its plant correlative, are the same all through 

 the organic world. The sensori-motor system — receptor 

 organ, nerve-fibre and cell, and effector-motor organ — 

 is the same all through the animal kingdom. Ali- 

 mentary canal and glands, enzymes, excretory tubules, 

 contractile blood-vascular apparatus — all these are 

 structures which are functionally the same, which are 

 built on essentially the same morphological plan. 

 Life, whether it is the life of plant or animal, makes use 

 of the same material means of perpetuating itself on 

 the earth and avoiding the descent of matter towards 

 complete inertia. 



Absolute dissimilarities, dissimilarities such as those 

 between atoms of hydrogen and oxygen, or between a 

 point and a straight line, or between rest and motion, 

 do not exist between the different categories of entities 

 that make up the organic world. Yet differences do 

 exist, and must we conclude that because these differ- 

 ences are not absolute ones, because they are differences 



