CHAPTER II 

 ORGANIC STRUCTURE 



I. CHEMICAL 



Organisms, still considered as natural things, have structure. 

 They have definite, specifiable shapes and dimensions ; they have 

 bodies, limbs, etc., that have definite proportions to each other ; 

 they have colours, consistencies, etc. — that is, they have external 

 morphology. They are composed of parts that become visible 

 upon dissection and they have definite and specifiable chemical 

 constitutions. 



It is quite impossible to consider this structure apart from 

 considering organic behaviour and functioning and (either 

 patently or surreptitiously) we introduce the latter notions into 

 descriptions of morphology and chemical structure. However, 

 it will be convenient for exposition to regard organisms, in 

 this place, from a static, rather than from a dynamic point of 

 view^ 



From the morphological standpoint organisms exhibit patterns 

 of structure and the number of such patterns (specific forms) 

 tends to be indefinitely great. Each pattern is exemplified in 

 many individuals and the numbers of individual exemplars also 

 tend to be indefinitely great. 



From the chemical standpoint there are also patterns of struc- 

 ture : in all organisms the characteristic substances of the bodies 

 are proteins, carbohydrates and fats, but different categories of 

 organisms exhibit different kinds of these general materials. 

 Plants have much cellulose in their bodies and may have silica 

 as the material of their skeletal parts ; some animals have siliceous 

 skeletons while most have calcareous ones ; and so on. The 

 number of organic chemical patterns is far more limited than 

 the number of morphological ones. 



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