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 
Fic. 52.—FRANz LEypic, 1821-1908 (April). 
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 
