1859.] on the Chronometry of Life, 119 



appropriately fitted for life in the open air, is timed to a certain rate 

 of progress ; so much work is to be done in so many days, neither 

 more nor less ; and on each day its appropriate and special portion of 

 the work. And it is evident that the time occupied in the process is 

 determined by the inherent properties of the Qg'g itself. For if the 

 eggs of any number of species be exposed to the same heat and other 

 conditions, in a hatching machine, then, as surely as the bird pro- 

 duced from each will be like its parents, so surely will it be hatched 

 in the same time as its parents were ; in other words, the observance 

 of a specific time-rate in the process of development is as exact as that 

 of any other specific character. 



With this observance of time in the development of the young 

 might be noticed that which is, commonly, coincident in the parent. 

 Not to cite the example of all the mammalia, that of pigeons might be 

 taken, in which, during the incubation of their eggs, the crops of the 

 parents are remarkably developed, so that they may be fitted for the 

 secretion of a fluid destined to make the food of their young offspring 

 more suited for their sustenance. The correspondence of these time- 

 rates, observed, at once, in the development of the young pigeons, and 

 in that of the crops of the parents, demonstrates, in both, a provision 

 for chronometry in their organic processes, as clearly as the faces of 

 two clocks, constantly keeping time together, would prove that they 

 both have some apparatus for chronometry within. 



Further, the provisions made by parents for their future young 

 afford evidence of the time-regulation of organic processes, in so far as 

 those provisions seem to indicate a reckoning of the time necessary for 

 their completion. For example, certain turtles lay their eggs in 

 hollows made in the sand, leave them there to be hatched, and at the 

 time of hatching return to them for the sake of their yonng. It might 

 be asked, how can these creatures, and many others in similar cases, 

 reckon the passage of time ? Most probably, they do not reckon it 

 at all ; but just as the timely attained fitness of their organization for 

 preparing and filling their nests impelled them to those acts, so some 

 time-regulated organic processes, taking place in them after the laying of 

 their eggs, bring about at length a new condition, of which a dim 

 consciousness becomes an impulse to them to return to their nests. 

 Such an explanation would involve little guess-work ; for changed 

 organization is, manifestly, often the source of impulse to instinctive 

 actions, and the parental organization does commonly change at a rate 

 commensurate with tliat of the development of the offspring. And a 

 similar reference to chronometric processes in the body, might explain 

 many, though probably not all, other instances in which animals seem 

 to have a power of reckoning the passage of time. 



The phenomena of disease, especially in fevers, agues, the conse- 

 quences of injuries, and many cutaneous eruptions, would afford abundant 

 instances of the observance of time in the organic processes. The 

 vaccine disease might be generally watched as an illustration, being 

 characterized by a vesicle at each place of insertion of the virus, which 

 vesicle begins to appear on the third day, and on the following days 



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