114 H ' L ' RAT CLIFFE. 



(Wilson, 1925). One cannot say just how far the nuclear mecha- 

 nism of this organism might bear out the principles of genetics 

 that have been proven in metazoan types, but the observations 

 seem to indicate that the chromosomes are composed of " self- 

 perpetuating bodies " aligned in a single series since the chromo- 

 some elements undergo a definite linear fission each time the cycle 

 is completed. 



3. Origin of the motor organelles of E. spirogyra is quite similar 

 to that reported for E. agilis Baker (1926). The mass from 

 which the kinetic elements arise is budded off from the endosome 

 during the period of reorganization following division, while Baker 

 found that in E. agilis this mass was given off in the prophase, 

 and, instead of the rhizoplast persisting as in E. spirogyra, the 

 mass leaves the nuclear membrane to form the " kineto-nucleus " 

 (Baker, 1926). Concerning this phenomenon in E. agilis Baker 

 concludes, " The endosome in E. agilis is the ultimate source of 

 all the kinetic elements of the cell. . . ." The same may be said 

 for E. spirogyra although the kinetic element is budded off at a 

 different time in the life cycle. 



Splitting of flagella during division has been described by Steuer 

 (1904) for Eutreptia, and Hall (1923) reported the same for 

 Menoidium incurvwn. One may easily see that the axial fibers 

 of E. spirogyra move apart during the prophase of division thus 

 splitting the old flagellum. As pointed out in the introduction, 

 Baker (1926) states that these organelles are lost during division 

 and originate anew for each daughter cell following division of 

 E. agilis. 



IV. SUMMARY. 



Nuclear division in Euglena spirogyra takes place within the 

 nuclear membrane, and no centriole appears during the process. 

 The nucleus moves forward into contact with the base of the 

 reservoir. The chromatin in the vegetative nucleus is in the form 

 of paired strands of chromomeres. These shorten and thicken 

 in the prophase and lose their granular appearance, forming the 

 chromosome pairs of the metaphase. The chromosomes are never 

 arranged in a true equatorial plate, but the members of each pair 



