80 . THE CELL DOCTRINE. 



The cause of this permanent staining of the ger- 

 minal matter by an ammoniacal solution of carmine, 

 is thought by Dr. Beale to be due to an acid reaction 

 of this matter, in consequence of which the carmine 

 is precipitated from its alkaline solution. This view 

 would seem to be confirmed by the researches of 

 Ranke on the Reaction of the Tissues. 



The size of the elementary part, as thus composed, 

 is extremely various. The smallest particles of ger- 

 minal matter, measured by Dr. Beale, are less than 

 TuAiji) f au mcn m diameter, and would not be 

 called cells in the ordinary sense of the word, yet 

 they are functionally such ; that is, they grow, multi- 

 ply by division, and under appropriate circumstances 

 assume the characters of fully formed cells. On the 

 other hand, the largest epithelial cells, including 

 their germinal matter and formed material, are often 

 as large as the 5^ of an inch in diameter, or larger; 

 cells of morbid growths are sometimes 2 J^, while the 

 human ovum, which is a typical cell, varies from the 

 24 s to T2TJ f an mc h- Pure germinal matter is rarely 

 seen in masses as large as the ? J^ of an inch in di- 

 ameter, without breaking up into smaller particles of 

 germinal matter, and as constituting the nuclei of 

 fully formed cells, is' usually from g^ to ^^ of an 

 inch in diameter. 



The method of production of formed material is best 

 studied in the epithelial structures, particularly in 

 the epithelium lining mucous cavities, of which sec- 

 tions may be easily made down to the vessels whence 

 their nourishment is obtained. In the deep layers, 

 next the nutrient surface, the cells will be found to 



