INTRODUCTION 



The purpose of Doctor Albert Fischer in \\ riting 

 this book was chiefly to describe the develop- 

 ment of the procedures by which the method of 

 tissue culture is becoming slowly adapted to its 

 main object, the study of the fundamental problems 

 in physiology and pathology. The early technique, 

 which was derived from the beautiful experiments 

 of Harrison and consisted in placing a fragment 

 of fresh tissue in a hanging drop of culture medium, 

 did not allow an accurate analysis of the action of 

 a tissue upon other tissues and upon the humors. 

 The cells were subjected to complex influences, 

 such as those of necrotic cells of their ow^n type, 

 of living and dead cells of other types, and of a 

 medium which deteriorated spontaneously in a short 

 time. It w^as as impossible to study cell physiology 

 with a fragment of tissue of complex composition 

 as to investigate the properties of bacteria living 

 in a medium contaminated by other bacteria. The 

 earlier techniques led to many errors, and had to 

 be profoundly modified before the method of tissue 

 culture could become an instrument of physiological 

 investigation. 



