336 BIOLOGICAL PHYSICS 



germinal spot, may be said to mark the origin of the 

 systemic nervous system, in its process of evolution from 

 the primitive developmental elements of the completely 

 formed spermo-germ body, and to represent the laying 

 down of the foundation members of the, greater, and 

 smaller, neuronal structures, comprised within the brain, 

 cord, and nerves, or systemic nervous system. The 

 elements of the embryo, from which the systemic nerve 

 structures are built up, are the first to respond to the 

 operation of the developmental impulse, and to betake 

 themselves to organised, and organising, activity, or to 

 the work of organisation, hence we find that, that organ- 

 ising work extends, in the directions in which the nerve 

 textures are, in future, to be discovered by the anatomist ; 

 the nerve elements would, therefore, seem to initiate, 

 dominate, and determine, the direction, and manner of 

 arrangement, of the non-nervous elements of the growing 

 embryo, consequently, we must recognise, that the nerve 

 structures, must inter-penetrate, and be co-terminous with, 

 all organised matter, and, also, that we must find actual 

 nerve plasma in the elements from which they are developed, 

 in all parts of the organic whole. These nerve elements, 

 originating at the centre, and being continued in unbroken 

 structural sequence to the periphery, of the body of the 

 embryo, and into its nascent muscles, necessitate not only 

 an unbroken histological connection, solid, liquid, or 

 plastic, but a formation, or growth, beginning at the 

 centre, progressing to the periphery, and muscles, and 

 terminating there, in exudation, or disruption, or by being 

 finally shed this peripheral disposal, taking the organised 

 forms of, epithelium, epidermis, hair, nails, etc., and the 

 sarcous elements of muscle. 



We are further of opinion, that the " process of growth " 

 of the systemic nervous system, begins in the sympathetic, 

 or truly trophic, neurons, if we may call them so, and 

 that these initiate, the process of growth generally, through- 

 out the entire area of developmental activity, not only 

 within the nervous system proper, but throughout the 

 musculo-skeletal, and the whole extent of the, so-called, 

 non-nervous, living tissues, and organs, this process of 

 growth being alike throughout the entire animal kingdom, 



