THE CELL DOCTRINE. 17 



rum," in 1670. He showed that the walls of the 

 " cells," or " vesicles," were separable, that they could 

 be isolated; and gave to each the name "utriculus" 

 believing also the "cell," or " utriculus," to be 

 an independent entity. The latter observer* also 

 recognized the blood .corpuscle. Leeuwenhoek, in 

 1687,f described these corpuscles with considerable 

 accuracy, not only in man, but also in the lower 

 animals. He also demonstrated the capillaries, ex- 

 amined most of the tissues, and made the discovery 

 of the spermatozoids, which he conceived to be sper- 

 matozoa or sperm animals, and of different sexes. 



No attempt, however, seems to have been intelli- 

 gently made at building up the tissues by an ultimate 

 physical element, to correspond with the "atom" of 

 the inorganic chemist, prior to that of Haller. He re- 

 solved the solid parts of animals and vegetables into 

 the "fibre" (fibra), and an "organized concrete." To 

 the former he assigns the most important position, 

 asserting that it is to the physiologist what the line 

 is to the geometrician; that a "fibre," in general, 

 may be considered as resembling a line made up of 

 points, having a moderate breadth, or rather as a 

 slender cylinder.;); 



The second elementary substance of the human 

 body according to Haller, the " organized concrete," 

 must not be lost sight of, as appears to have been 



* Malpighi, Opera Posthuma. London : 1697. 



f Leeuwenhoek, Opera Omnia sou Arcana Naturae detecta. 

 Tom. ii, p. 421. Leyden : 1687. Vel Opera Omnia, &c., Lugd. 

 Batav. : 1722. 



J Haller, Elementa Physiologiac, vol. i, lib. i, sect. i. Lausan. 

 Hclvet.: 1757. 



