CLASSIFICATION OF LIVING TYPES 59 



thousands of years or merely short fractions of a 

 second, they begin to lose their stability on account 

 of radiation, and thus break down again. 



The building up may, however, be brought about 

 in other ways, by the presence of a nucleus, which 

 can give rise to aggregations, by coagulations, and 

 catalytic actions, and by other means. 



The method of the formation of these molecular 

 aggregates will form the subject of a special chapter, 

 and we need not for the present dwell upon it here 

 with much more than a passing hint. It is doubtful 

 if a clear understanding of the precise method by 

 which it is effected can in all cases be formulated 

 with precision : but it will then be, and it certainly 

 now is, sufficient for our purpose to know that such 

 integrations can, and do, take place. Whatever 

 difi&culties may arise, and in some cases such diffi- 

 culties are sure to arise, in picturing to ourselves the 

 actual manner by which such complex aggregates are 

 built up, we shall for the present content ourselves 

 and be pleased to assume that they can be formed. 

 It is enough for our purpose at the present juncture. 

 We know they can be formed, and are so formed. 

 What more do we want for the purpose of classi- 

 fication ? 



Having thus started with the assumption that the 

 vital principle is in bodies which grow and also 

 in the course of time disintegrate, we can extend the 

 limits of the conception of vital action to the simplest 

 metabolism. The cyclic process of the self-integra- 

 tion and disintegration of the individual is a 



