NATURAL HISTOEY OF ORGANIZED 130DIES. 301 



must recur indefatic^ably to the study of particular facts, aud that, without renounc- 

 ing the purpose of reducing' them ev^entually to simjth' Laws, it is necessary in 

 the first pLicc to refer them to other special laws, but to such laws as are sus- 

 ceptible uf demonstration. 



Upon these grounds, certain phenomena of life may already be referred to 

 demonstrable laws. M. Brown-Se(piard, in particular, has given us, in his Journal 

 dc la Flujsiologic, a short note containing a very noticeable attempt at that gen- 

 eralization of which I have been speaking. This physiologist sets forth, as 

 results of his own labors as well as those of the savants who have preceded 

 him, ttvelve laws relative to the conditions under which nervous and muscular 

 actions are either produced, increased or exhausted, together with certain other 

 analogous phenomena which are observed in animals.* 



Among these laws there are several which are not, perhaps, be3'ond the reach 

 of criticism, and everything would lead us to believe that the further progress of 

 science will reduce them to greater simplicity. Such as they are, however, they 

 appear to me well worthy of remark and meditation. For some of my auditors, 

 it is true, this generalization may be premature and difficult of comprehension; 

 but for most of those who are somewhat initiated in biology, I would hope that 

 they might lead to an enlarged conception of the facts with which they are 

 already acquainted. Some of these laws, being those which are specially appli- 

 cable to muscular contraction, are in substance as follows: 



FiKST LAW. — Muscular contraction seems in scixir able from an organic change 

 which nutrition alone can repair. 



It is now known that the muscle in repose presents the alkaline reaction, and 

 that, under the influence of repeated contractions, it passes to the acid reaction; 

 a chemical process has therefore been at work, which has modified the composi- 

 tion of the muscle. Again, if we seek in a muscle the proportion of matter solu- 

 ble in water, before or after energetic exertion, we shall tind, with Helmholtz, 

 that the quantity of soluble substances has augmented under the influence of 

 that exertion. 



Second law. — The rapidity of the circulation of the Wood and the richness of 

 that liquid in restorative substances, favor the recuperation of the muscle, and ren- 

 der it capable of new labor. 



This law, like the preceding, is susceptible of experimental verification. We 

 can augment or diminish the time necessary for the recuperation of the muscle 

 by abating or accelerating the course of the blood which traverses it. The need 

 of alimentation which follows muscular exercise also confirms this law in what 

 relates to the influence of the qualities of the blood on the muscular restoration. 

 Even in the absence of circulation, the restoration still takes place within certain 

 limits, which is explained l)y the presence of the blood with which the tissues 

 are saturated, even w'hen it ceases to circulate. 



Thikd law, (flowing from the two preceding). — A muscle is subjected to 

 two influences, the one restorative, nutrition ; the other exhaustive, its motive func- 

 tion ; its actual faculty of producing movement varies according as one or the 

 other of these influences has acted. 



Hence, after a prolonged repose, the muscle has attained its maximum of 

 aptitude to act, since the restoration is produced without w^aste. Conversely, 

 after prolonged action, the faculty of acting is at its minimum. It will be seen 

 how closely this law approximates to laws purely physical, and how much the 

 muscle resembles an apparatus w'hich on the one hand receives electricity, and 

 on the other dispenses it ; as it does also a body subjected to a source of heat and 

 to an intermitting cause of refrigeration. 



Fourth law. — Becuperation after action is more rapid during the first few 

 instants than it is afterwards. 



* In the number of these would further appear the electric phenomena observed in certain 

 fishes, the phosphorescence of certain animals, the movement of vibratory cilia, &c. 



