72 THE CELL DOCTRINE. 



similarity of the mobile phenomena of the Polytha- 

 lamiae with those of the processes of protoplasm 

 stretched across the cavity of many vegetable cells. 

 Although he had not personally investigated the 

 former, he became convinced from Schultze's de- 

 scription, that a resemblance amounting to identity 

 existed between their movements and the protoplasm 

 streams of vegetable cells."* 



Shortly before this, Pringsheimf (1854), showed 

 that no such membrane as a primordial utricle ex- 

 isted, but that all within the cellulose wall of the liv- 

 ing vegetable cell was protoplasm and cell fluid, how- 

 ever complex its composition. 



"He admitted that in the cortical layer of the pro- 

 toplasma a distinct arrangement into layers often 

 occurred, and these he distinguished as the cutane- 

 ous and granular layers of the protoplasms, but he 

 denied that the primordial utricle could be differen- 

 tiated as a membrane from the subjacent protoplasm. 

 If, in animal cells, partly from their relatively small 

 size, and partly from their greater average wealth in 

 protoplasma, it is more rarely possible to make a 

 sharp demarcation between a cortical layer of pro- 

 toplasm and a cell fluid, there nevertheless exists a 

 difference in the constitution of the former, such 

 that a cutaneous layer, destitute of, or scantily sup- 

 plied with granules, incloses the remaining more 

 granular material. The white blood-cell may serve 



* Duffin, A. B., On Protoplasm. Quart. Jour. Mic. Sci., N. S., 

 vol. iii, 1863, p. 252. 



f Pringsheim, Untersuchungen uber d. Bau. u. d. Bildung d. 

 Pflanzenzelle. 1854. 



