ISOLATED EFFECTS OF BEAUTIFUL PROPORTIONS. 405 



A. Conditions of the Motor en Mode de Masse, or of Force. 



The subjects intended for this kind of work are vulgarly known 

 by the names heavy draught-horses, horses of force. Their value is 

 proportional to the burden which they are capable of displacing, at the 

 slowest gait, by the contraction of their muscles. Let us see upon 

 what depends the intensity of this contraction, and what external signs 

 denote it. 



A muscle is a particular group of red fibres, collected in bundles ordinarily 

 parallel, decomposable by histological analysis into very fine fibres endowed with 

 special irritability and contractility. In the physiological state this property acts 

 under the influence of a stimulation proceeding from the nervous centres ; it 

 shows itself by a more or less marked, energetic, and rapid diminution of the 

 length of the primitive fibrillse. Connective tissue isolates and at the same time 

 conjoins the elementary parts of the muscle ; abundant vessels (arteries) carry to 

 it materials for its nutrition and its activity ; others (veins and lymphatics) carry 

 away the wastes of its functional activity ; finally, whitish cords (nerves), termi- 

 nating in its mass by numerous filaments, veritable conductors, connect it with 

 the nervous centres, and transmit to it the motor stimuli from the will. These 

 last reach the organ in such a way that all its elements contract simultaneously, 

 producing, by this very means, a total shortening of variable extent. 



The weight susceptible of neutralizing the movement which results from 

 this gives the measure of what is vulgarly called the contractile force of the 

 muscle. Whence it follows that the force of a horse, in relation with a determined 

 effort, would be also approximatively indicated by the total or the sum of the in- 

 dividual actions of the agents which accomplish this effort. In other words, it 

 would be the weight which he is apt to move in conditions when the speed 

 appears insignificant, although, rationally speaking, it is never thus. 



In this case, we see, force is created at the expense of speed ; in fact, we do 

 not regard as important the quantity of the space passed over ; it is sufficient 

 for us that the animal moves the obstacle. 



Now, the manifestation of this phenomenon obeys the two following 

 conditions : 



1st. The number of the contractile elements, and the particular 

 nature of their incidences upon the locomotory levers. 



2d. The intensity of the nervous stimulation. 



All things being equal, it is plain that, of two muscles whose fibres 

 have the same/orce, the one which has them in double quantity will be 

 twice as strong as the other. It is none the less evident that if, by 

 some mechanical disposition, one of these muscles is placed in a condi- 

 tion to act in a more perpendicular direction, it will do its work easily 

 or will be able to overcome a greater resistance. 



As to nerve stimulation, physiology teaches that it reaches the 



