342 WOOLFORD B. BAKER. 



is rounded or knob-like while the other is blunt and possesses an 

 elongation on the anterior side, from which the intra-nuclear 

 rhizoplast may be traced to the kinetic complex. As division 

 progresses and the centrodesmose elongates, the opposite ends of 

 the endosome seem to be drawn upward toward the two kinetic 

 centers, or rather the two masses from which the motor elements 

 have been developed. The mass of the endosome appears as a 

 passive frame work or support serving as a central spindle for the 

 division process, and not as a kinetic center for the division. 



Whitmore (1911) describes in Proivazekia asiatica a process 

 quite similar to that observed in Euglena agilis. According to 

 him a body is pinched off from the karyosome which has loosened 

 up during the early stages of division. From this body arise the 

 centrioles while the remainder of the karyosome together with the 

 outer chromatin of the nucleus forms the spindle. He concludes 

 that the body pinched off is the locomotor-generative component, 

 the karyosome residue constituting the idio-chromatin. 



In diphasic amebse which combine amoeboid and flagellated 

 phases in one life cycle, e.g., Nxgleria gruberi (Wilson, 1915), a 

 granule in the endosome gives rise to the blepharoplast by 

 division. One daughter-granule destined to become the ble- 

 pharoplast, migrates to the nuclear membrane, remaining con- 

 nected with the granule in the endosome by an intra-nuclear 

 rhizoplast. The flagellum grows out from the blepharoplast, 

 hence the motor apparatus in these forms arises directly or 

 indirectly as an outgrowth from the endosome. The process in 

 Euglena agilis is not quite as simple as this since the mass budded 

 from the endosome contains blepharoplasts, basal bodies, and a 

 chromatoid residue, which remains in close connection with the 

 motor apparatus until the daughter animals become fully re- 

 organized after division. 



McCulloch (1917) describes the origin of a chromatoid mass 

 from the endosome in Crithidia euryophthalmi. This mass later 

 is seen connected with the blepharoplast and the endosome by 

 means of rhizoplasts. She identifies the structure as the para- 

 basal body. A somewhat similar body is figured in Cryptobia by 

 Swezy, who likewise speaks of it as the parabasal body. The 

 resemblance between these figures and certain stages in the cycle 

 of Euglena agilis is readily seen (Text-figure A}. 



