REACTIONS OF CELL-BODIES OF DIFFLUGIA. 37 



Willis, and Mast and Root have found, therefore, that enucleated 

 fragments of protozoa do not respond normally, while Verworn 

 and Lynch find that katabolic activity is normal on the part of 

 these enucleated fragments of protoplasm. In Difflugia we have 

 found a response that is remarkably well regulated and very deli- 

 cate. This is of especial interest because the fragments which we 

 were dealing with were only ectoplasmic in composition. 



We wish to avoid the implication that the regulated movements 

 of these ectoplasmic fragments were effected without nuclear con- 

 trol, for the absence of nuclei in them does not preclude nuclear 

 influence. Regulatory substances of nuclear origin might have 

 been present in the ectoplasmic fragments at the time they were 

 severed from the cell-body. For, as Minchin (p. 65) states, "in 

 many protozoa, especially amongst the Sarcodina, as, for example, 

 Arcella, Difflugia, and many other genera, the cell-body contains, 

 in addition to one or more nuclei, extranuclear granules of chrom- 

 atin, termed chromidia, which may be scattered in the cytoplasm 

 throughout the cell, or may be aggregated in certain regions of the 

 body to form ' chromidial masses ' or ' chromidial nets.' " 



Regulatory movements between a fragment and a cell were not 

 maintained when a fragment was taken from an individual of one 

 species and placed by the side of an individual of another species. 

 This is in accord with the observations of Wilson (1907), who 

 found that in dealing with dissociated sponge cells, " in contact 

 two masses of the same specific protoplasm tend to fuse," while 

 "unlike specific substances (protoplasms of quite different species) 

 do not tend to fuse." In Difflugia protoplasms from two different 

 species do not fuse or coalesce. Also the following quotation from 

 Lillie (1920) can be applied to our findings on Difflugia: "If we 

 put two different species of yeast or bacteria into the same culture- 

 medium, each builds up protoplasm of its own kind; i.e., each 

 effects a special predetermined kind of chemical transformation in 

 the materials which it incorporates from the surroundings. Each 

 has the same external materials as its source of supply, but each 

 transforms them in its own specific way, and hence builds up a 

 special kind of protoplasmic structure which, having a special 

 physio-chemical constitution or organization, exhibits corresponding 

 special activities. The term specificity denotes this peculiarity." 



