SOME MOOT POINTS 7JT A'ATCKAL HISTORY. 257 



facts and ideas regarding the constitution of the living body. 

 The progress of microscopic and chemical science, so far 

 from resting at the discovery of cells and of their qualities, 

 served to open up a vista of large extent, along which the 

 lines of scientific thought were already beginning to travel, 

 in the direction of demonstrating a still closer unity of form 

 and composition between animals and plants. Gradually 

 the idea that cells represented a stage in which a certain 

 work of formation had already been begun and completed, 

 grew upon the minds of physiologists. "What preceded 

 the cell?" and "From what was the cell itself formed?" 

 were questions which naturally suggested themselves to 

 observers. After the excitement which had ensued on the 

 physiological contest, which might well be named " the battle 

 of the cells, had subsided, and after the various theories 

 regarding the paramount importance of one or other part of 

 the cell had been duly ventilated, physiologists were led to 

 see that a certain substance which had been greatly over- 

 looked in their discussions, held a place of high importance 

 in the life and structure, not only of cells, but of the bodies 

 of animals and plants at large. This substance was found 

 to enter into the composition of cells of every kind. It 

 appeared to form the active and essential element in these 

 bodies, and constituted a substance upon which the in- 

 crease of cells, and through the cells the growth of the 

 living body at large, depended. This matter is that now of 

 world-wide celebrity, and known under the name of " Proto- 

 plasm;" and it may fairly be said that whatever be the 

 views held by physiologists as to its connection with the 

 life it exhibits, this substance may most appropriately be 

 named the "physical basis of life/' Life, as far as the 

 furthest research has shown, does not exist apart from this 

 protoplasm. A mere speck of this matter, destitute of 

 definite structure or parts, constitutes a living being, able, 

 as exemplified by the yeast-plant, or by the structureless 

 proteus animalcule or amceba (Fig. 41), to cam- on all the 

 functions of life, as perfectly, regarded with reference to the 



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