746 THE POPULAR SCIENCE MONTHLY. 



been assigned the duty of building up structure and of transforming 

 the energy of lifeless matter into that of living. 



To suppose, however, that all protoplasm is identical where no dif- 

 ference cognizable by any means at our disposal can be detected would 

 be an error. Of two particles of protoplasm, between which we may 

 defy all the power of the microscope, all the resources of the labora- 

 tory, to detect a difference, one can develop only to a jelly-fish, the 

 other only to a man, and one conclusion alone is here possible that 

 deep within them there must be a fundamental difference which thus 

 determines their inevitable destiny, but of which we know nothing, 

 and can assert nothing beyond the statement that it must depend on 

 their hidden molecular constitution. 



In the molecular condition of protoplasm there is probably as much 

 complexity as in the disposition of organs in the most highly differen- 

 tiated organisms ; and between two masses of protoplasm indistin- 

 guishable from one another there may be as much molecular difference 

 as there is between the form and arrangement of organs in the most 

 widely separated animals or plants. 



Herein lies the many-sidedness of protoplasm ; herein lies its sig- 

 nificance as the basis of all morphological expression, as the agent of 

 all physiological work, while in all this there must be an adaptiveness 

 to purpose as great as any claimed for the most complicated organism. 



From the facts which have been now brought to your notice there 

 is but one legitimate conclusion that life is a property of protoplasm. 

 In this assertion there is nothing that need startle us. The essential 

 phenomena of living beings are not so widely separated from the phe- 

 nomena of lifeless matter as to render it impossible to recognize an 

 analogy between" them ; for even irritability, the one grand character 

 of all living beings, is not more difficult to be conceived of as a prop- 

 erty of matter than the physical phenomena of radial energy. 



It is quite true that between lifeless and living matter there is a 

 vast difference, a difference greater far than any which can be found 

 between the most diverse manifestations of lifeless matter. Though 

 the refined synthesis of modern chemistry may have succeeded in form- 

 ing a few principles which until lately had been deemed the proper 

 product of vitality, the fact still remains that no one has ever yet built 

 up one particle of living matter out of lifeless elements that every 

 living creature, from the simplest dweller on the confines of organiza- 

 tion up to the highest and most complex organism, has its origin in 

 preexistent living matter that the protoplasm of to-day is but the 

 continuation of the protoplasm of other ages, handed down to us 

 through periods of indefinable and indeterminable time. 



Yet with all this, vast as the differences may be, there is nothing 

 which precludes a comparison of the properties of living matter with 

 those of lifeless. 



When, however, we say that life is a property of protoplasm, we 



