THE SEED 71 



What is it, then, that disturbs this equilibrium, and, so 

 to speak, transfers the centre of gravity from the 

 endosperm to the embryo ? How can we explain this 

 transfer of substance from the endosperm to the embryo? 

 We can do so in the same way as in our last lecture we 

 explained the passage of the iron salt from the outer 

 vessel into our artificial cell, by the reconversion of the 

 diffusing substances into insoluble compounds. The 

 substances in solution which penetrate into the embryo 

 are used up in the development of new organs. Glucose, 

 a soluble carbohydrate, is thus converted into the 

 insoluble carbohydrate cellulose, of which the walls of 

 the new cells are built up. The soluble and diffusible 

 albuminoids are transformed into the insoluble and non- 

 diffusible protoplasm of these cells. This transforma- 

 tion, as we already know, will cause the diffusion of 

 fresh quantities of glucose into the embryo, and so on. 

 This dissolution and precipitation of substances in a 

 seedling, this drift of matter from endosperm to embryo, 

 will continue as long as they are in contact with one 

 another. Let us imagine that two persons have agreed 

 to share their movable belongings from time to time in 

 equal parts ; then let us suppose that one of the two 

 persons is so imprudent as to gradually exchange his 

 immovable property into movable, whereas, on the 

 contrary, the other exchanges part of his movable 

 property for immovable. In the end all the property 

 of the former will have passed into the hands of the 

 latter. This is precisely how an embryo acquires its 

 food from the endosperm and the cotyledons. It 

 absorbs the food because of its growth, and it grows 

 because of the food it absorbs here cause and effect are 

 mutually connected very intimately, as they are in any 

 vital function. 



We therefore see that underlying the nutritive 

 phenomena of the embryo there are the same general 

 phenomena of diffusion and transformation, by means of 



