6 THE GENERAL CHARACTERS OF CELLS, BY S. STRICKER. 



the views of histologists away from the idea of the vesicular 

 construction of cells. As has already been stated, Max Schultze 

 had himself furnished a new definition of a cell, which con- 

 stituted an extension of the theory of Schwann. Max Schultze 

 also defined the cell to be a little clump of matter (proto- 

 plasm), with a nucleus. The importance of this definition, 

 however, did not lie in the fact that the existence of a mem- 

 brane in many cells was denied that had been already more 

 or less positively stated before Max Schultze. The essential 

 point was, that the identity of the so-called cell contents 

 with the primary animal substance, or sarcode, was clearly 

 recognised. 



Little advance had, indeed, been made in the way of estab- 

 lishing a basis of life ; for nothing more was known of the 

 processes which take place in the living substance, than of 

 those that were carried on in vesicles perhaps still less for 

 all the phenomena of diffusion were intelligible on the vesicular 

 theory, whilst it was difficult now to account for them. Na- 

 turalists, however, were familiar with irritable independently 

 existing animals, but not with the idea of an irritable 

 and independent vesicle obtaining its food by the laws of 

 diffusion. The conception of a living cell body, or elementary 

 organism (Briicke), has been an exceedingly satisfactory one 

 /to biologists, on the same principle that it gives us a great 

 degree of satisfaction to be able to attribute to some familiar 

 I circumstance a noise in our sleeping apartment, on the origin 

 of which we have long speculated in vain. 



Those membranes of the animal cell which did not exhibit a double 

 contour, were compared by intelligent histologists, not with the cel- 

 lulose investment, but with the primordial utricle of the cells of plants. 

 Botanists* distinguish a cellulose investment in the cells of plants, with- 

 in which is the protoplasm that includes the nucleus and the solid 

 and fluid contents of the cell. The protoplasmic mass externally, 

 where it comes into contact with the wall of cellulose, was supposed 

 to be invested by a very thin membrane the primordial utricle. But 

 Pringsheimf has shown that such a primordial utricle does not exist, the 



* H. v. Mohl, Vermischte Schriften, Botan. Inhalts, 1845. 

 f Ban und Bildung d. Pflanzenzellen, 18o4. 



