LECTURE III 

 THE GENERAL PHYSICAL CONSTITUTION OF LIVING MATTER 



i. THE LIMITS OF DIVISIBILITY OF LIVING MATTER 



THE preceding lecture has shown that living matter is a mixture of 

 various compounds, namely proteins, fats, carbohydrates, and salts. The 

 fact that the reaction velocity for a number of oxidative and hydrolytic 

 processes is so great, in spite of the low temperature and the practically 

 neutral reaction of the tissues, has found its explanation through the 

 presence of specific enzymes and the intermediary reactions determined 

 by them. If we ask whether it would suffice for the purpose of making 

 living matter to try to find a mixture of the above-mentioned substances, 

 including the enzymes, the answer would have to be no, for the reason 

 that living matter is characterized by another peculiarity not yet men- 

 tioned, namely, a definite structure. 



Whatever may be the physical structure of living matter, it is certain 

 that in most cases its complete destruction means the cessation of life 

 phenomena. A brain or kidney which has been ground to a pulp is no 

 longer able to perform its functions; yet it is evident from the facts 

 mentioned in the previous lecture that certain chemical functions can 

 still be performed by such pulps, e.g. the catalytic processes. The 

 question now arises as to how far the divisibility of living matter can be 

 carried without interfering with its functions. Are the smallest particles 

 of living matter which still exhibit all its functions of the order of magni- 

 tude of molecules and atoms, or are they of a different order? The 

 first step toward an answer to this question was accomplished by Moritz 

 Nussbaum,* who found that if an Infusorian be divided into two pieces, 

 one with and one without a nucleus, only the latter will continue to live 

 and perform all the functions of self-preservation and development 

 which are characteristic of living organisms. This shows that not 

 only more than two definite substances, but two different structural 

 elements, are needed for life. We can understand partly from this 

 why an organ after being reduced to a pulp, in which the differentia- 



* Nussbaum, loc. cit. 

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