1916] ^Yihon: On the Life-History of a Soil Amoeba 269. 



the flagella grow out. These increase in length as the nueleus gets 

 closer to the basal granule, evidently at the expense of the rhizoplast 

 and nuclear plastin. 



(6) Process of ex flagellation. — In material fixed one hour after 

 having been stimulated to exHagellate, amoeboid individuals with 

 shorter flagella and elongated karj'osomes and those with blepharoplast 

 or with none distinguishable are to be found. In the latter case the 

 karyosome looks like that of the early stage of entlagellation (pi. 22, 

 fig. 101). However, this may be due to a pull on the karyosome. 

 Sometimes there is a stainable mass on the rhizoplast midway between 

 the periphery and the nucleus (pi. 22, fig, 100). The flagella have 

 been observed during the process of being pulled in in living material. 

 The indications are that the material returns to the nucleus. Early 

 exflagellation begins with a change in form (pi. 22. figs. 100-103). 

 Stages are found in the same material with granule connected with the 

 karycsome (pi. 22, fig. 104) and with an elongated pointed karyosome 

 and no flagella or peripheral chromatin. 



These facts of themselves are incomplete and inadequate, but taken 

 together with those of enflagellation, it seems clear that the basal 

 granule resumes its position in the karyosome, and that the plastin, 

 both flagellar and that of the rhizoplast, is drawn in and takes up its 

 position with the basal granule within the nucleus. 



C. SEXUAL STAGES IN CULTURES 



Gametogenesis and syngamy have not been conclusively found in 

 the cultures. In the cysts, i.solated instances of conditions simulating 

 maturation have been found, and binucleate trophozoites and flagellates 

 simulating syngamy occur. In old cultures it is very common to find 

 one large chromidium and the luicleus with its chromatin broken up 

 (pi. 21, fig. 86) superficially suggesting a maturation division. Some- 

 times the nucleus is large and somewhat elongated and the chromatin 

 has a form which closely resembles a spindle (pi. 21, fig. 8.5) but no 

 spindle fibers have been found and the chromatin is not in a regular 

 equatorial plate between the two .small spherical granules, but it so 

 closely resembles an equatorial plate that it is with difficulty that its 

 banded nature is detected. Sometimes a cyst has been found with one 

 large chromidium in the cytoplasm and with two nuclei, in each of 

 which the chromatin was broken up so that it resembled a spireme with 

 its nucleolus. In some cultures, in which multinucleate forms were 



