AS THE ELEMENTAL GERM OF AN ORGANISM 341 



functions, all of which are only perceptible to us collectively, are 

 resolved into their true elements in the idioplasm." Such 

 elements, according to de Vries, are the particles which are able 

 to form chlorophyll, the colouring matter of flowers, tannic acid 

 or essential oils, and we may add muscular tissue, nerve tissue, 

 etc. 



Similar ideas are expressed in a somewhat different form, and regarded from 

 other points of view, by Sachs (IX. 25) in his essay " Stoff und Form der 

 Pflanzenorgane." Here he says, " we are forced to assume the presence of as 

 many specific formative materials as there are definite forms of organs to he 

 distinguished in a plant." We must therefore imagine that "very small 

 quantities of certain substances are able so to influence those masses of 

 materials, with which they are mixed, that they induce them to set into 

 different organic forms." 



Although at present we cannot with any degree of certainty 

 define the specific nature of a single idioblast, we are able to draw 

 fairly definite conclusions regarding some of their common 

 properties. 



It is, of course, first necessary to consider, that the hypothetical 

 idioblasts must possess the power of multiplying by means of 

 division, like the higher elementary units, the cells. For the egg 

 imparts to each of the two cells into which it divides, and these 

 again to the daughter-cells, which are derived from them, certain 

 particles, which are the bearers of specific properties. Hence a 

 multiplication of these particles must take place during the differ- 

 ent processes of development ; they must further be able to go on 

 dividing, and in consequence must possess also the power of growth, 

 without which continuous divisibility is inconceivable. Darwin, 

 Nageli, and de Vries, therefore, logically assume that their gem- 

 mulae, particles of idioplasm, and pangenae, are both able to grow 

 and to divide. 



This assumption enables us to draw another conclusion about the 

 nature of the idioblasts, viz. that by their very nature they can- 

 not be identical with the atoms and molecules of the chemist and 

 physicist ; for the former are indivisible, and the latter, although 

 divisible, split up into portions, which no longer possess the 

 properties of the whole. A definite molecule of albumen cannot 

 grow without changing its nature, for when it takes up new groups 

 of atoms, it enters into new combinations, by which means its 

 properties are altered. Neither can it break itself up into two 



