360 . Dynamic Theory. 



before polar action can begin to reproduce it. Suppose that every sort 

 or species of tissue in the bocty is represented in the reproductive nu- 

 cleus or seed by one molecule or group of molecules ; when the whole 

 aggregation is immersed in a solution containing materials for all, they 

 must select and assimilate these materials in the construction of a form 

 to correspond with their constitution and polarities. So that the differ- 

 ence between a crystal and a so-called vital organism is one chiefly of 

 degree, not of principle. 



CHAPTER XXXVIII. 



POLARITY IN ORGANIC ELEMENTS. 



The molecules that go to make up the various tissues of the organized 

 body, all possess form and polarity peculiar to themselves, and the 

 tissue to which each molecule belongs occupies a relationship to it simi- 

 lar to that occupied by a mineral crystal to its component molecules. 

 The tendency of the tissue is, like a crystal, to preserve its shape when 

 finally formed, and when some of its molecules are disrupted the polar 

 attractions of the remaining molecules are exerted to win similar particles 

 from the dissolved organic molecules of the blood to fill up the void and 

 make the repair. Thus in a healing ulcer the new skin grows from the 

 edges of the sore in connection with the epidermal cells already there. 

 In order to hasten the healing process, surgeons sometimes transfer a 

 small piece of epidermis from some healthy part of the body to the middle 

 of the sore to be healed, and the new skin then grows from the edges of 

 this, and it is observed that, as it approaches the margin of the sore, it 

 stimulates the production of new tissue there if sluggish as it sometimes is. 



It is well known that minute fragments cut from a hydra or from a 

 medusa, when placed in suitable situations, are capable of developing 

 into perfect organisms similar to those from which they had been de- 

 rived, just as a mere fragment of a crystal thrown into an almost super- 

 saturated solution of the same salt will lead to the formation of a perfect 

 crystal. No less than forty perfect polypes have been produced from 

 the mince meat of a single one. We are told, moreover, by Dr. Hooker, 

 that there is a species of Begonia, the stalks, leaves and other parts of 

 which are superficially studded with loosely attached cellular bodies, and 

 that any one of these bodies, if placed under favorable conditions, will 

 produce a perfect plant similar to its parent. The power of a part re- 

 producing the whole is seen daily in the processes adopted and practiced 

 by fruit growers. A mere stick of a grape cutting, providing it has a 

 bud, will grow into a complete vine, and the same is true of willow and 

 many other plants. In root grafting, a piece of root of apple or other 

 tree, four or five inches long, is split for a distance of an inch and a 



