374 



The Unity of the Organism 



tions advanced in favor of the view that it is partly determined 

 by the ectoplasm, are essentially the same as those for the view 

 that the flagella are thus produced. The particular point to which 

 attention is now called is the view held by Maier, and apparently 

 well supported by observations, that the membrane is the result 

 of a fusion of a row of cilia. The evidence for this is the 

 cross-striation of the membrane and the presence of a row of 

 thickly set, darkly staining granules at its base. If this sup- 

 position is correct the question arises, where is the "seat" of the 

 developmental tendency which brings about the fusion of the 



FIGURE 21. FROXTOttIA T.EUC'AS, THKITOCYST (AFTER 



ju'h., axial rod. ;ichr., achromatinic substance, h., head, n., neck. 

 inn., 1 unclear membrane. 



cilia? "Is it the basal granules or some other elements aside from 

 the material of the cilia themselves? Or is it produced, as Maier 

 says, by an "adherence of the neighboring cilia through a plas- 

 matic substance"? Obviously there can be but one answer if it 

 is to be based on the observational evidence. 



Let us now return to the development of the trichocysts of 

 Frontonia which we partly examined in the last section (figure 15, 

 p. 327) . That the chromatin of the macronucleus contributes di- 

 rectly to the organs was shown in the section dealing with the di- 

 rect evidence that chromatin may be "hereditary substance." But 

 it was there stated that the chromatin was not alone concerned in 

 their production. Now we must instruct ourselves as to what 



