104 THE LESSON OF EVOLUTION 



material vestiges remain in the nervous system, by 

 which the nervous substance is enabled to reproduce 

 such physical processes as are connected with the 

 psychical processes, or sensations and perceptions. 

 Repetition increases the power of reproducing the 

 sensations. But, after all, memory is chiefly a 

 faculty of unconscious life. Memories only emerge 

 occasionally into conscious life ; and it is this un- 

 conscious memory which produces unity in our 

 actions and prevents each conscious action from 

 being isolated and independent. Habitual perfor- 

 mance of an action makes it easy to do ; and this 

 is only possible by the central nervous system being 

 capable of reproducing the former states of irritation. 

 It remembers, after practice, what it did before. 

 The unconscious memory of the sympathetic system 

 is as strong as that of the brain. In the same way 

 muscles grow stronger from use, and so do all the 

 other systems. They also can perform their func- 

 tions better after repeated practice. 



Now the nervous system is a coherent unity, 

 probably connected with every cell, [and it might 

 have been added that all the cells of a plant are. 

 connected by threads of protoplasm.] Any irritation 

 effected in one part is re-echoed by the others ; and 

 this re-echo w r ould probably be stronger in the re- 

 productive cells than elsewhere. The reappearance 

 of the parent in the full-grown offspring can only 

 be due to the reproduction of such processes as the 

 germ had previously taken part in, while still in the 

 reproductive organs. The offspring remembers 

 those processes, so soon as the same or similar 



