334 Organic Nature s Riddle 



or parenchyma, of our own body transforms part of what 

 is immediately external to it into the parenchyma itself. 

 Again, the process of secretion is, as it were, parallel to the 

 process of alimentation or nutrition. In secretion, the body 

 extracts from the blood new substances (the secretions) which 

 do not exist as such within it. In nutrition, the body ex- 

 tracts from the blood new substances (the various tissues) 

 which do not exist as such within it. The blood is not the 

 only source of our nutrition, since it has the power of 

 replenishing itself. Thus the living particles which form 

 the ultimate substance of our body exercise a certain power 

 of choice with respect to the contents of the fluids which 

 come in contact with them. Such particles are not passive 

 bodies ; they are active living agents, and their action no 

 one has yet really explained. Here, then, are a set of 

 activities which, if duly pondered over, will be found to 

 be fully as mysterious and inexplicable in their unconscious 

 teleology as any phenomena of instinct as ordinarily under- 

 stood. But there is another class of organic vital actions 

 which also seem to have a decided affinity both to reflex 

 action and to instinct, though they are not to be regarded 

 as actual instances of either of these faculties. The actions 

 I refer to are those which bring about the repair of injuries 

 and the reproduction of lost parts. They are hke reflex 

 action inasmuch as they take place in perfect unconscious- 

 ness and without the will having any power over them. 

 They are like instinct inasmuch as they are directed towards 

 a useful and unforeseen end. In the process of healing and 

 repair of a wounded part of the body, a fluid, perfectly 

 structureless substance, is secreted, or poured forth, from the 

 parts about the wound. In this substance cells arise and 

 become abundant ; so that the substance, at first structure- 

 less, becomes what is called cellular tissue. Then, by degrees, 

 this structure transforms itself into vessels, tendons, nerves, 



