'models of living organisms' 87 



mechanistic in character. These attempts were made at the 

 beginning of the present century because many biologists 

 of that time considered that the cause of the vital properties 

 of protoplasm resided only in its structure, that is, in its 

 specific spatial configuration, while completely ignoring the 

 metabolism, that form of the motion of matter which is 

 characteristic of life. 



At that time they conceived the spatial organisation of 

 protoplasm in terms of a machine ; a definite construction 

 formed from some sort of solid and unchanging interrelated 

 ' beams and braces '. From this point of view the structure 

 of protoplasm with the rigidly determined spatial arrange- 

 ment of its parts was the specific cause of life in the same 

 way as the disposition of the wheels, beams, pistons and other 

 component parts of the mechanism determine the particular 

 function of a machine. 



L. Jost^^ wrote as follows : 



The functioning of a machine does not depend primarily on 

 the chemical properties of its components but on their arrange- 

 ment and interrelationship. We may construct a machine of 

 brass or of steel and this will certainly affect its durability and 

 accuracy but will not affect the nature of the work it does. 



Similarly, Jost held, the activity of living cells depends 

 more on the arrangement of their parts than on the composi- 

 tion of the protoplasm. It follows that the direct route to 

 the understanding of life is not through the study of the 

 metabolism and other vital phenomena but through the 

 investigation of the structure of protoplasm and the spatial 

 arrangement of its parts. 



The next stage in the historical development of the subject 

 lay in the attempt to see directly, through the microscope, 

 the spatial configuration which formed the basis of life, and 

 the belief that this attempt was only unsuccessful because of 

 the insufficiency of our optical methods. If we could see the 

 finest details of the structure of protoplasm we should thus 

 understand life itself. The actual working out of this prin- 

 ciple, however, only led to bitter disappointments. The 

 simple observation of living cells under the microscope gave 

 very little indication of a machine-like structure of proto- 



