THE RELATION OF CELLS TO ONE ANOTHER 217 



architect to direct the execution of the plan, because the 

 hving units themselves understand the requirements of the 

 whole and act according to it, through a process which has 

 no analogy in nature. Cells can be compared to stones which 

 might have the magical power of setting themselves in order 

 and making a wall, even when there is no house to be erected 

 and no mason to build it. Possibly there is some remote 

 analogy between the behavior of tissue elements and that 

 of ants or bees which bhndly work for the interest of the 

 community. But the manner in which final causes seem to 

 act upon efficient causes is as mysterious in the case of 

 insects as in that of cells. Biology is not at present in a 

 position to give any general explanation of organization 

 and of the teleological processes responsible for it. We must 

 patiently bring into the experimental field the mechanisms 

 which cause, partly at least, the unity of the body. After an 

 extensive analysis of the elementary processes, the horizon 

 may broaden, and the veil may be lifted. But all is still 

 very dark. Even if the ultimate mystery of organic unity 

 should never be understood, this investigation of the inte- 

 grating principles will be far from useless. It is bound to 

 supply medicine with most important information about the 

 mechanisms which are involved in the formation and 

 maintenance of the wholeness of the body, and to increase 

 its power for curing diseases and improving the quality 

 of human beings. 



REFERENCES 



Bridgman, p. W. 1927. The Logic of Modern Physics. N. Y., Macmillan. 

 Carrel, A. 1923. A method for the physiological study of tissues in vitro. 

 J. Exper. Med., 38: 407. 

 1924. Tissue culture and cell physiology. Physiol. Rev., 4: i. 



1927. La cytologic nouvelle. Cornpt. rend. Soc. bioL, 96: 1198. 



1928. Modern techniques of tissue culture and results. Archiv. J. exp. 

 Zelljorscb., 6: 70. 



Carrel, A., and Ebeling, A. H. 1926. The fundamental properties of the 

 fibroblast and the macrophage, i. The fibroblast. J. Exper. Med., 44: 261. 



1926. II. The macrophage. J. Exper. Med., 44: 285. 



1928. III. The malignant fibroblast of sarcoma 10 of the Crocker Foundation. 

 J. Exper. Med., 48: 105. 



1928. IV. The malignant fibroblast of Jensen sarcoma. J. Exper. Med., 

 48: 285. 



