118 Mr. Paget, [Aprils, 



and then growth ceases and the body is only maintained in its perfec- 

 tion, so, after a time of such maintenance, the method of the formative 

 processes in the body changes, it slowly degenerates, and through de- 

 generacy dies. And all these stages are, alike, natural, constant, 

 timely ; all, too, are together, characteristic of life ; there is no such 

 succession of events to be traced in any form of dead matter. 



Observance of time may, again, be noted in the formative pro- 

 cesses concerned in any of the organs whose changes mark the divisions 

 of a life into its chief periods ; e.g. in the teeth. Considering merely 

 the conditions in which the teeth of the first set are placed before they 

 project from the gums, there appears no reason why one should be cut 

 before the other, or why they should not all grow with equal speed. Yet 

 while they all grow alike in regard of structure and composition, they 

 have very difterent rules in regard to the time-rate of their formation. 

 And a yet more marked instance of time-regulation is in the contrast 

 of the teeth of the first set with those of the second. In all essential 

 characters, except those of strength and size, the two sets are much 

 alike ; yet there is the widest difference in the rates at which they are 

 formed, and in their duration. The second teeth require as many years 

 for their formation as the first require months ; the first live but a few 

 years, the second should live as long as the rest of the body, and some- 

 times do so. Now there appears nothing to which, as to an efficient 

 cause, this difference can be referred. Its utility and final cause can 

 be discerned ; but, as to that which verily determines the rates of 

 growth, and the durations of the teeth, it can only be referred to a 

 First Cause ; or it may be said, as of other things subordinate to a First 

 cause, that it depends on some of those properties which each living 

 being inherits from its parents, and through which it results that, in 

 respect of time, as well as of method and quantity, the formative 

 processes in the offspring are a repetition of those of the parent. 



The observation of the development and changes of the teeth affords, 

 moreover, an excellent instance of the punctuality with which time- 

 work is regulated in the organic processes, and of the manner in which 

 several different, and really independent, processes, being set to the 

 same time-rate, are made to co-operate to the end of utility in the 

 economy. This is evident in the coincidence of the development of 

 the teeth of the second set, with the removal of those of the first ; and 

 in the coincident growth of the jaw, and all its muscles and other 

 apparatus for mastication. In all of these (and the same might be 

 said of any other system of organs in any species) the formation of 

 every part is achieved with an admeasurement of time as precise, and 

 as perfectly designed, as that of its shape, or size, or structure. 



For examples of organic processes, . adjusted to be complete in 

 definite periods of time, the germination of seeds, and the hatching of 

 eggs, could be cited. In plants, and in cold-blooded animals, the time 

 varies according to temperature, yet not without evidence of a proper 

 time-rate ; but among birds, each species has its own time for incuba- 

 tion, as fixed as its other specific characters. In other words, the 

 development of the structures of an egg into those of a young bird, 



