118 



BIOLOGY OF THE PROTOZOA 



the centrodesmose in Metazoa, remain outside of the nucleus (as 

 it does in many other flagellates) and is called the paradesmose by 

 Kofoid to distinguish it from the centrodesmose or central spindle. 

 From this review of the cytoplasmic kinetic elements in the flag- 

 ellates it is apparent that in endobasal bodies, basal bodies, and 

 parabasal bodies we have to do with structures closely connected 

 with the kinetic activities of the organism and closely related to 

 each other. The chromatoid substance of which they are composed 

 may or may not be chromatin, although the evidence adduced indi- 

 cates that it arises from the nucleus and in some cases is similar to 

 chromatin in its staining reactions. It does not behave like chro- 



^V^' V^Vf -V-V^C" 



" i, J, ^ ■*.**--. A « L.vJ '/ 



Fig. 64. — Trichonympha campanula Kof. and Swez. (After Kofoid and Swezy.) 



matin during division of the cell, but like pyrenoids, or chromato- 

 phores, where each granule reproduces its like by division; nor 

 does it afford any evidence of constructive metabolic activities in 

 the cell. For these reasons I believe, with Kofoid, that the term 

 "parabasal body" expresses the relationships and functional activi- 

 ties of the so-called "kinetonucleus" much better than does the 

 latter term and should take its place in literature dealing with the 

 Protozoa. The interpretation of kinetonucleus and parabasals, 

 however, is still incomplete. In Trypanosoma, as stated above, the 

 kinetic element known as the "kinetonucleus" (aud.) or the "para- 

 basal" (Kofoid, Swezy, et al.) gives a positive Feulgen nucleal 

 reaction, indicating the presence of thymonucleic acid (Bresslau and 

 Scremin, 1924; Robertson, 1928; Jirovec, 1927; DaCunha and 



