PREFACE Ix 



therefore begin our discussion by reviewing the ini- 

 tial experiments concerning the toxic nature of shock. 



A portion of the contents of the first few chapters 

 may not appear to be of immediate interest to the 

 general biologist. However, the investigations dis- 

 cussed therein really formed the basis of the author's 

 concepts, which have been extended to some problems 

 of distinct general interest. In essence, the experi- 

 mental evidence appears to indicate that under ap- 

 propriate stimulus, living cells appear to be able to 

 yield an endocellular component which is capable of 

 both exciting and depressing the activities of neigh- 

 boring cells. For want of a better name, this substance 

 has been termed cytost, and is so designated through- 

 out the present discussion. The postulation of the 

 existence of cytost and its role in the physiology of 

 living systems was necessitated in order to explain 

 and harmonize a diversified series of experimental 

 observations. 



All that one may ask of any scientific theory is that 

 it satisfactorily explain known facts and if in the fu- 

 ture new facts are found which are not in harmony 

 with that theory, then the theory must be discarded. 

 Hence if in the future the author's cytost concept is 

 replaced by some other hypothesis, it matters little. 

 For the present the cytost concept is of service in 

 interpreting the meaning of performed experiments 

 and in guiding the imagination of the investigator in 

 the conduct of new experimental researches. Thus, 

 as will be shown later, the cytost concept has enabled 

 us to explain the curious stimulating effects of ex- 

 hausted soil upon the growth of plants in virgin soil. 

 To be sure, this appears to be a far cry from the cause 



