214 



THE AMEBIC AN NATURALIST [Vol. LI 



of the flagellates when stained on the slide present a 

 lateral aspect as shown in Fig. 2, since they fall over on to 

 their side in the drying out of the tilm. 



But the appearance of the flagellate as described above 

 does not endure for very long, simply because the tropho- 

 zoite stage itself does not endure. The development of 

 the trophozoite marks the period of 3"outh, and when the 

 organism has sufficiently fed on bacteria and cocci, and 

 obtained a sufficient amount of reserve food, it passes on 

 either into division or into a form of autogamous repro- 

 duction by which the flagellate population is increased at 

 a rapid rate. 



In the case of division, the process seems to be for the 

 most part longij;udinal. The first indication of it is to be 

 seen in the blepharoplast-complex and in the nucleus. 

 From each new blepharoplast there appears to grow out a 

 new chromatic line, extending more or less parallel to the 

 old line. From these new lines the new undulating mem- 

 branes appear to arise. The writer has not been able to 

 observe the division-stages of the flagella, although stages 

 have been seen in which new flagella are present in con- 

 nection with each new blepharoplast. Neither has it been 

 possible to follow the changes in the axostyle. As to the 

 chromatic blocks, these also seem to disappear and are 

 probably formed anew in the daughter cells. 



But reproduction by division, though occurring com- 

 monly in the intestinal content, is probably not the chief 

 method of reproduction. At all times, though at some 

 times more markedly than at others, the flagellates enter 

 into a course of autogamous reproduction in which several 

 daughter cells are formed out of a single mother cell. 

 This interesting process can be followed in considerable 

 detail by means of suitably stained smear preparations. 



The first step in this process is the " r oun ding- off " of 

 the previously elongate or crescentic trophozoite after it 

 has reached maturity. If the body-form was crescentic 

 there occurs a filling-out of the concave surface so that at 

 first a full oval shape is produced; later the organism be- 

 comes spherical. This rounding-off process, which is 



