THE FUNDAMENTAL ORGANIZATION 



61 



finally, there is no evidence at all of kinetic elements in resting 

 nuclei, but collections of homogeneous substance (karyolymph) are 

 present at the poles of the nucleus during division (pole plates). 



1. Large Homogeneous Endobasal Bodies. — In this type the endo- 

 basal body is conspicuous by its large size and homogeneous struc- 

 ture. It was first described by Kenten (1895) in Euglena viridis 

 and was early recognized as a kinetic element connected with 

 nuclear division as attested by the names intranuclear centrosome, 



Fig. 29. — Bodo ovatus Stein (edax, Belaf). (1) Vegetative individual with two 

 flagella; blepharoplast (bl) and nucleus with endosome. (2 to 6) Division of the 

 basal bodies, blepharoplast and nucleus; (7 to 10) completion of nuclear division and 

 division of cell body. (After Belaf, from Doflein.) 



division center, etc., applied to it, while nuclei containing it were 

 included by Boveri in his "centronucleus" type. In Euglena viridis 

 and euglenoids generally, this endobasal body according to earlier 

 descriptions of Keuten, Tschenzoff (1916) and others is the most 

 conspicuous structure of the nucleus, where, in the resting nucleus, 

 it appears as a spherical or elongated ellipsoidal body with chromatin 

 granules of limited number suspended between it and the nuclear 

 membrane. It divides prior to division of the chromatin, first 

 elongating with a concentration of its material at the poles. The 



