3 72 'Journal of Co?nparative Neurology and Psychology. 



tions arising in one part of the body being impressed on other parts 

 dynamically without interchange of substance. He says "the com- 

 munication of idioplasmic peculiarities occurs either in a material 

 or a dynamic manner." The first method suffers from the diffi- 

 culty of explaining the diffusion of colloid micellae through living 

 membranes (cell walls). This difficulty he evades by assuming 

 that all cells of the body communicate by means of fine pores, 

 thus forming paths of communication permitting actual exchange 

 of substance between distant parts of the body. In the case of a 

 dynamic interpretation he finds it necessary to assume either that 

 vibrations pass through the cell walls or that they are transmitted 

 via the pores above postulated. He remarks, however, that if 

 material mixture and intercourse does occur it is nevertheless 

 probable that equilibrating communication occurs as a dynamic 

 process. This is worthy of careful consideration. No matter 

 how far one may go in the attempt to explain vital function by 

 means of structure, in last analysis, the effect of part on part is 

 always to be construed in dynamic terms. 



The communicating avenues which we are daily coming to rec- 

 ognize as existino; in and between the reticula of all cells (corre- 

 sponding to Naegeli's Micellreihen.) are but the evidences of 

 dynamic communication of one order but they do not exhaust the 

 possibilities. Because the molecules are dynamically yoked in 

 constant interaction by chemical combinations this does not pre- 

 vent the larger groups from being connected by larger (non-chemi- 

 cal) bonds no less real. 



Very interesting from a dynamic point of view are recent obser- 

 vations and theories of egg maturation and development. We 

 have progressed very far beyond a purely mechanical theory of the 

 building of the body out of cells as a house may be built out of 

 bricks. The importance of the cytoplasmic elements of localiza- 

 tion and differentiation suggested by Lankester's theory of pre- 

 cocious segregation and culminating in Roux's mosaic theory of 

 development becomes clear through later observations by Wilson, 

 Yatsu, and others. 



That a high degree of prelocalization or cytoplasmic organization 

 exists in the unsegmented egg has long been clear. Wilson's 

 work undertakes to discover whether the prelocalization of the 

 morphological factors exists from the beginning or whether it is a 



