122 The Unity of the Organism 



we shall come upon that which, to a large extent, has de- 

 termined the present writer's attitude toward protoplasm. 



To begin with, there can be no doubt that, historically 

 considered, "protoplasm is a biological conception," as O. 

 Hertwig insists.^ Furthermore, equally certain is it that 

 when so considered it is a term of descriptive biology pure 

 and simple. The discoverers of protoplasm were engaged 

 in the enterprise of describing and comparing the minute 

 structure of animals and plants, no less avowedly than the 

 discoverers of the capillaries of the blood system were en- 

 gaged in the same enterprise. They were telling what they 

 saw under their microscopes and were drawing conclusions 

 from their observations. Even the titles of many of the 

 foundational memoirs of the protoplasm theory show this. 



On the plant side, Corti (1772) was describing what he 

 saw in the interior of the living twigs of Chara; Meyen 

 (1827) what he could see in the fresh leaves of water-celery 

 {V allesnaria) ; Robert Brown (1831) what the living hairs 

 of the still higher plant Tradescantia revealed to him, and 

 so on. Similarly from the account left by Rosel V. Rosen- 

 hof (1755) of the examination of his "Proteus animalcule" 

 we know he had an amoeba under his microscope and was 

 studying it as he had numerous other organisms, low and 

 high, to find out how it was constituted. It was what seemed 

 to Dujardin (1855) the resemblance of the soft, living mate- 

 rial of the foraminifera examined by him, to the flesh of 

 liigher animals that made him propose the name sarcode for 

 this material. Finally, to mention no others of the many 

 whose observations contributed to the upbuilding of the 

 science of microscopic anatomy, it was Max Schultze's exam- 

 ination of the minute structure of a great range of animals 

 and animal tissues, from amoebae and the foraminiferae to 

 the muscles and retinas of the 'higher vertebrates, that fur- 

 nished the raw materials for his splendid inductions. 



If we inquire how a strictly objective discovery concern- 



