HO H. L. RATCLIFFE. 



(1923) have described division of the blepharoplast, and Hall 

 obtained evidence that the old flagellum split to form two new 

 ones during cell division in Menoidium incurvum. The motor 

 organelles of Euglena agilis have been found to disintegrate and 

 blepharoplasts originate anew from the endosome, from which 

 grow the flagella of the daughter organisms (Baker, 1926). In 

 Heteronema acus, a biflagellated form, the original flagella per- 

 sist and new flagella are produced during division, one for each 

 daughter cell (Rhodes and Brown, MS.). 



The mitotic process of Euglena spirogyra lends itself readily 

 to the further study of these problems because of its large nucleus 

 and easily studied cytoplasmic structures. 



II. MATERIAL AND METHODS. 



The euglenas were grown in finger bowls of 200 cc. capacity 

 on a modification of Doflein's flagellate culture medium (see 

 " Lehrbuch der Protozoenkunde, Vierte Auflage," p. 371, F. 

 Doflein) made up in tap-water. It was found that, following ex- 

 posure to several hours sunlight, division occurred in abundance, 

 beginning about two hours after sunset, and approximately all 

 forms dividing on any given day began fission within an hour 

 after this time. The process was completed within 3-4 hours, so 

 that by fixing material every half hour one obtained a well-con- 

 nected picture of division. 



Fleming's and Schaudinn's fluids were used with equal success. 

 Material was killed en masse after centrifuging about one half a 

 minute, and was allowed to stand in the fixative for about 30 

 minutes. Shorter fixation was not satisfactory. After this it 

 was thoroughly washed in distilled water and run through the 

 alcohol series to 85 per cent, alcohol in which it was allowed to 

 stand three or four days to remove the chlorophyll. From the 

 alcohol the material was fixed on slides with egg albumen and 

 stained with aqueous iron alum haematoxylin, counterstaining with 

 eosin or orange G. Other stains were used but these did not give 

 the differentiation necessary for studying mitotic figures. The 

 entire process of mitosis was also observed in the living material 

 with oil immersion lens. Continued exposure to the light of the 

 microscope caused nuclear division to cease, but after nuclear 



