THE BIRTH OF HISTOLOGY 175 



parliament. He assisted in molding the cell-theory into 

 better form, and in 1858 published a work on Cellular 

 Pathology, which applied the cell-theory to diseased tissues. 

 It is to be remembered that Bichat was a medical man, in- 

 tensely interested in pathological, or diseased, tissues, and we 



FIG. 52. FRANZ LEYDIG, 1821-1908. 



Courtesy of Dr. Wm. M. Wheeler. 



see in Virchow the one who especially extended Bichat's work 

 on the side of abnormal histology. Virchow's name is asso- 

 ciated also with the beginning of the idea of germinal conti- 

 nuity, which is the basis of biological ideas regarding hered- 

 ity (see, further, Chapter XV). 



Leydig. Franz Leydig (Fig. 52) was early in the field 

 as a histologist with his handbook (Lehrbuch der Histologie 



