66 THE CELL DOCTRINE. 



is true of all physiological and pathological processes 

 in the vegetable and animal. In all editions of 

 "Cellular Pathology" which we have met, the 

 'typical cell is described as consisting essentially of 

 "cell-wall," "cell contents," and "nucleus;" the 

 " nucleolus," though usually met in fully developed 

 older forms, is not considered an essential constit- 

 uent of the cell. The object of the " nucleus," ac- 

 cording to Virchow, is entirely connected with the 

 life of the cell, that which maintains it as an element 

 and which insures its reproduction. While to the 

 " cell contents " over and above the nucleus, that is 

 the " residual cell contents," is due the function of 

 the cell, that to which is due the contractility of 

 muscle, the neurilityand sensation of nerve, and the 

 secretory office of the gland cell.* 



To secure the universal application of the cell 

 doctrine, it becomes necessary to eliminate from the 

 vegetable cell, the external non-nitrogenous mem- 

 brane, known as cellulose, and restrict it to the nitro- 

 genized portion comprised in the primordial utricle 

 as the proper cell-wall, and in the ■protoplasmic con- 

 tents of the cavity as the proper cell contents, which 

 contain also the nucleus. " It is only when we ad- 

 here to this view of the matter, when we separate 

 from the cell all that has been added to it as an after- 

 development, that we obtain a simple, homogeneous, 



* Virchow, Cellular Pathology, as based upon Physiological 

 and Pathological Histology. Sebond Edition. Translated by 

 Prank Ohance, M.B., etc. Am. Edition, Philadelphia, 1863, p. 

 37. 



