88 THE BIOLOGICAL PROBLEM OF TO-DA Y 



tozoon are cells the possession of characters not 

 peculiar to cells, but resulting from the co-operation 

 of many cells. 



The characters of an adult active organism, like 

 a plant or an animal, are exceedingly numerous, 

 most varied in their nature, and essentially differ- 

 ent. Some characters depend upon the healthy 

 co-operation of nearly all the parts of the body, or 

 of a group of organs ; others are peculiar to an 

 organ, and may be referred to its shape, structure, 

 position, function, and so forth. Others, again, 

 depend upon individual cells, or even upon sepa- 

 rate parts of cells. Is it really possible that all 

 these characters, so many and so heterogeneous, 

 have special, material bearers in the germ, and 

 that these bearers are either simple biophores or 

 determinants that is to say, groups of biophores ? 



I can conceive a cell as endowed only with the 

 material bearers of such characters as really belong 

 to a cell itself. Thus, a reproductive cell might have 

 material particles as the rudiments for producing 

 horn, chitin, chondrin, ossein, pigment, or chloro- 

 phyll, or for nerve-fibrils, muscle-fibrils ; but not 

 for producing a hair, or a separate ganglion of the 

 spinal cord or the biceps muscle. The rudiments 

 for hairs, nerve-ganglia, muscles, and so forth, must 

 be groups of cells, for only groups of cells, and not 

 specially arranged groups of particles within a cell, 

 are able to grow into hairs, spinal ganglia, or muscles. 



In a short statement, made in 1892, I said : ' The 

 mistake into which speculations upon the nature of 

 organic development has led so many investigators 



