496 The University Science Bulletin. 



damental reaction of the fixed tissues otherwise remains the same. 

 The only exception to this rule is to be found in the wandering cells. 

 These cells have not been observed to grow in the cultures. They 

 have also lost their ability to cause a true coagulation of the plasma. 

 They occasion the gelation of the clot and can move only in contact 

 with this jelly like mass, but they cause no fibrin formation. They 

 owe their spherical shape to their inability to form true surfaces in 

 the medium. They move by a mechanism different from the fixed 

 tissue. They can invade these fixed tissues in the presence, at least, 

 of an exudate. When this disappears they tend to move back into 

 the lymphatics and blood capillaries. They do not repel strongly 

 the moving fixed tissues like the fixed tissues repel each other. They 

 have lost the property to form the "L" substances. I say they have 

 lost it because it is present in the mother cells from which the wan- 

 dering cells arise. 



To what extent this chemical differentiation is reversible like that 

 peculiar to -the mechanical form I have not definitely determined. 

 There is evidence to show that the mesenchyme cells may arise from 

 epithelial cells even in late embryonic life, but for the most part 

 these epithelial cells maintain their chemical peculiarities for a 

 long time in cancerous growths and in the cultures. I have seen 

 heart-muscle cells assume the characteristics of large mononuclear 

 cells. The reverse has not, however, so far been proven. Again 1 

 have seen liver cells, after repeated transplantation, behave in part 

 at least like the connective-tissue cells. There is no reason to be- 

 lieve, however, that such chemical dedifferentiation may not occur 

 and maintain in the proper environment. 



The cells of the organism are not, therefore, highly complex sys- 

 tems. They are not equipped to lead an independent existence. 

 They do not age. They have no organization for work. They pro- 

 duce the energy, but the work or their various manifestations of life 

 is dependent wholly upon external conditions about them. The 

 only form of work depending on an evident internal organization is 

 cell division. The forces active in the process center about the 

 centrosomes. There is no evidence, however, that activation of these 

 centers, or even their formation, is controlled from within. The 

 centrosomes develop probably alone in response to external stimuli 

 (see Hertwig, Meade, Morgan, J. Loeb, E. B. Wilson^ and others). 



Energy production in these cells is again wholly dependent upon 

 organization, or the presence of specific substances which split or 

 otherwise make the removal of the "L" substances possible. Their 



