The Organism and Its Cells 177 



give a false impression of their true nature. If they are 

 to be called "cultures," then tlie word must be understood 

 to have a somewliat different meaning from what it has 

 in ordinary biological technology, where the production of 

 true organisms is always contemplated. Indeed the distinction 

 is at least partly recognized by Carrel and Burrows, for in 

 one of their publications they say: "Since the tissues, in 

 their development, must adapt themselves to the morpholog- 

 ical plan of the organism, their growth must be constantly 

 regulated by some iniknown factor. This regulation may be 

 caused by certain chemical compounds contained in the 

 blood and the interstitial lymph. . . . Therefore, it may be 

 assumed tliat the power of growth is kept under constant 

 restraint, that every organ is compelled to follow the mor- 

 phological plan of the organism, and normal plasma is far 

 from being the optimal medium for the culture of normal 

 cells." 4"^ 



Now that we are learning so much about the part played 

 by chemical messengers, or hormones, in normalizing growth 

 (see Chapter 18, in Part II of this book), the conception 

 that "every organ is compelled to follow the morphological 

 plan of the organism" is gaining intelligibility. 



This statement goes, by unmistakable inference at least, 

 to the very heart of the matter. Even were it demonstrated 

 that embryonal cells and organs are capable of developing 

 into perfectly normal adult parts when isolated from the 

 embryos, this would prove that these cells and organs are 

 capable of independent life in an ontogenic sense only. It 

 would not prove them so independent in a full sense, that 

 is, in a phylogenic as well as an ontogenic sense. 



The very fact that the adult organs into which they 

 developed could be pronounced normal would mean that their 

 development was, in Carrel and Burrows' language, "com- 

 pelled to follow the morphological plan of the organism." 

 In other words, the development would be guided by heredity 



