1900 ] 105 



sympathetic system is hard to conceive, but substitute a food-bond, and 

 the connection is at once obvious, and easy of comprehension. 



The case would be strengthened, too, if we could only show that 

 structure was in the habit of being modified by the nature of the 

 food taken in the ordinary way through the digestive system, but 

 among animals the only instance I can call to mind is that presented 

 us in the development of the queen and neuter bees. The fact is, the 

 animal economy is so self-contained that the ingesta, however varied 

 within certain limits their nature may be, are all resolved by digestion 

 into much the same substances. Plants, however, stand on a different 

 footing ; in them environment often masters heredit}^ instead of 

 heredity overpowering environment, as in the animal, and the cause of 

 this great difference is to be found, I venture to suggest, in the 

 reversed positions of the soma and germ-matter in these two funda- 

 mental divisions of the organic world. In the animal the germ-matter 

 is internal, and jealously guarded from all outside influence, except 

 what can reach it indirectly through the containing gland (ovary or 

 testis), whilst the active though less plastic soma is external and in 

 immediate relation with the environment. But in the plant the soma 

 is represented b}' the woody and hardly living internal skeleton, and 

 it is the germ-matter that is outside and in full contact with the en- 

 vironment, being packed away among the actively growing parts (the 

 liber, &c.), much in the same way as it is in the stroma of the testis 

 or ovary of the animal. And the result, if not the object, is that in 

 the one case the form is stable, and the influence of the environment 

 reduced to a minimum, in the other the stability is lessened and the 

 environment enabled to obtain freer play. This is amply born out by 

 a reference to the practice of those engaged in improving our domes- 

 ticated races, whether animal or vegetable. In the rearing of his 

 fancy stock the animal breeder depends solely on selection and judi- 

 cious crossing, but the raiser of plants, besides these resources, can 

 actively control his results by modifying in various ways the general 

 conditions, among which the nature of the soil and all which that 

 implies is the most important. In plants, therefore, we must conclude 

 that structure does largely depend upon food. 



Again, the phenomena of gall -formation offer perhaps a still 

 more striking illustration of this dependence. Galls are in reality 

 most extraordinary bodies ; their strange forms, so unlike any of the 

 natural parts of the plant, their altered tissues and complex structure, 

 and the power possessed by some of them of growing and maturing 

 after being shed by the parent plant show how profoundly the proto- 



