CHAPTER V 



PHYSICAL NATURE OF PROTOPLASMIC STRUCTURE: 

 IMPORTANCE OF SURFACE CONDITIONS 



It is not possible here to review in detail the numerous 

 and frequently conflicting conceptions of protoplasmic 

 structure. The details made visible by microscopical 

 technique are of so varied a kind that none of the many 

 attempts at unification have met with universal agree- 

 ment. A chief difficulty has been that most histological 

 investigators seem to have conceived of protoplasmic 

 structure as existing independently of the chemical and 

 physiological activities of the living system, and not as 

 both dependent upon and determining these activities. 

 Some conception of structure is required which will be 

 general enough to apply to all of the forms of living 

 matter, and which will at the same time enable us to 

 understand the dependence of the fundamental vital 

 properties of specific synthesis and irritability upon 

 structure. It may be doubted whether we are yet in a 

 position to form a clear and permanently valid concep- 

 tion of protoplasmic structure, but with the progress in 

 our knowledge of the properties of colloidal systems has 

 come what appears to be an increased insight into the 

 possibilities. The problem may be defined in its essential 

 terms, as follows: Can a system, with components of the 

 kind which we find present in all living matter, be ima- 

 gined which will exhibit, as a correlative of its structural 

 composition, the above-described properties of specific 

 growth, sensitivity to electrical conditions, catalytic 



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