THE CELL DOCTRINE. 31 



healthy animal cells, and in the germ cell or ovule of 

 birds, as early as in 1825, by Purkinje ;* while Pur- 

 kinje,t Valentin,;]: and Turpin,§ had actually called 

 attention to the relations of the animal and vegetable 

 cell to each other. 



The pr'e-existence of the nucleus, and the gradual 

 development of the cell about it, Valentin had at- ^ 

 tempted to demonstrate in the case of pigment cells, 

 C. H. Schultzll in the blood-corpuscle, Rudolph Wag- 

 ner in the egg, and Heule in epithelium, all before 

 the work of Schleiden had appeared. Miiller had 

 also insisted on the analogy between the cells of the 

 chorda dorsalis and vegetable cells.T Valentin, too, 

 had said, when describing the nucleus,of epidermic 

 cells, which he was the first to point out, that they 

 reminded him of the nucleus of the cells of vege- 

 table tissues.** Not only this, but Armand de Qua- 

 trefagesft and Dumortier:j::|: had actually observed the 

 origin of young cells from' the full grown, in the 



* Purkinje, J., Ev. Symtolse ad ovi avium historiatn ante incu- 

 bationem, cum duobus lithographs. Vratis., 1825. 



f Purliinje and Easchkow, Meletemata circa Mammaliura Den- 

 tium Evolutionem. Diss. Inaug. Vratis., 1835, p. 12. 



\ Valentin, TJeber den Verlauf und die Enden der Nerven, aua 

 den Nov. Act. Nat. Curios., vol. xvii ; besonders abgedruckt. Bonn, 

 1836. 



\ Turpin, Ann. d. Sci. Nat., 2 ser. vii, 207. 

 II Sehultz, C. H., Mailer's Archiv fur Anatomie, Physiologie 

 und Wissenschaft. Med., p. cvii, 1837. 



\ Strieker, Manual of Human and Comparative Histology, 

 New. Syd. Soc. Translat., 1870, p. 1. 

 ** Valentin, Nov. Act., N. C. xvii, pt. I, p. 96. 

 +f Quatrefages, Annales des Sci. Nat., 2 ser. ii, p. 114. 

 \% Dumortier, Annales des Sci. Nat., 2 ser. vii, p. 129. 



