OF THE VITAL POWERS.. 21 



and probably the greater part of the function of se- 

 cretion.* 



43. So much in regard to the vital powers displayed 

 by motion (37, 39, 42). We have now to speak of 

 sensibility, which is peculiar to the nervous medulla 

 communicating with the sensorium. It bears the title 

 of vis nervea, and is the cause of perception when irri- 

 tation is excited in parts to which it is distributed, f 



44. The order which we have followed in enume- 

 rating the vital powers, (38, 43) is that in which they 

 successively arise both during our formation and after 

 birth. 



The nisus formativus must take place before we can 

 ascertain the existence of the new conception. 



Then contractility is exerted in the gelatinous sub- 

 stance of the embryo. 



When the muscular fibres are produced, they acquire 

 irritability. 



In those few organs whose motions cannot properly 

 be referred either to contractility or irritability, there 

 next exists a vita propria. 



Finally, after birth, sensibility is superadded. 



45. Similar also is the order, according to which the 

 vital powers, both common and proper, are distributed 

 to the organised bodies of each kingdom. % 



* On the vita propria of the absorbent vessels consult Seb. Justin. Brug- 

 mans, De Causa Absorptionis per Vasa Lymphatica. Lugd. Bat. 1795. 8vo. 



On the peculiar vital properties of the arteries consult Chr. Kramp, Kritik 

 der Praktischen Arzneikunde. Leipzig. 1795. 8vo. 



Many of the phenomena now mentioned are ascribed by others to an orgasm, 

 to use an old expression, struggling from the centre to the circumference, and 

 lately designated vital turgor. 



f Fouquet, Dictioimaire Ency elope" dique de Paris. T. xv. Art. Sensibiliti. 



X Consult C. Fr. Kielmeyer, Uber die Verh&ltnisse der organischen Kra/te 



