INTRODUCTION 11 



over the approximated edges of the injury. After the 

 juices from the flesh had started the healing process, 

 the wound was stitched together and dressed with an 

 antiseptic, stimulating honey. 



Lamarck, in seeking to explain the influence of such 

 environmental factors as light, temperature, pressure, 

 motion and use, imagined that these physical factors 

 set in motion "certain subtle existing fluids that cease- 

 lessly flow," bathing the body cells in a vitalizing 

 medium. While it is unlikely that Lamarck knew of 

 Imhotep's speculations, it is of some interest that he 

 assigned an important role to a subtle entity ever 

 present in the tissues, in much the same fashion as did 

 Imhotep. 



Although at the outset such conclusions appear to 

 savor strongly of the metaphysical, the author has 

 been forced to assume a somewhat analogous hypothe- 

 sis in order to effect a rational explanation of the re- 

 sults of his experiments conducted during the last 

 forty years. These experiments, which have covered 

 a variety of biological problems, have led to results 

 which can be interpreted only on the assumption of* 

 the elaboration by tissue cells of some substance which 

 is capable of modifying the activities of other cells. 

 This substance, which has been termed cytost, appears 

 to be capable, depending upon its concentration, of 

 exerting either a stimulating or toxic action upon cells 

 with which it comes in contact. 



In the 1880's the writer observed that slightly muti- 

 lated plants outgrew controls. Some years later it was 

 found that in animals a slight injury frequently pro- 

 duced a similar stimulating efifect upon the animal, 

 whereas a more extensive injury resulted in a depress- 

 ing or morbid effect. As will be shown in the succeed- 



