TRICHOMONAD FLAGELLATES. 349 



The spheroidal or ellipsoidal nucleus generally has a single (PI. 7, 

 P'ig. 79) large central karyosome or prior to mitosis several large ones 

 (Fig. 81). Its membrane is intact at all times and the peripheral 

 chromatin is not evident in decolorized nuclei. The intranuclear 

 cloud (PL 7, Fig. 79) is less in evidence, as is also the extranuclear one 

 (Fig. 85), than in Trichomonas augusta where cytoplasmic chromidia 

 are abundant. 



Binary Fission in Eutrichomastix serpentis. 



Both binary and multiple fission occur here as in Trichomonas. 

 Both are by divisions of the premitotic type with differentiated chro- 

 mosomes, intact nuclear membrane, and intranuclear spindle with 

 extranuclear paradesmose as described in Trichomonas. 



The first indication of mitosis is the faint intranuclear cloud (PI. 7, 

 Fig. 79) followed by an increase in the amount of chromatin and its 

 aggregation in a number of large granules which towartls the end of the 

 prophase form four chromatin masses or chromosomes (PI. 7, Figs. 

 82, 83). 



During this phase the blepharoplast divides, and the daughters 

 migrate to the poles of the elongating nucleus, spinning out a deeply 

 stained extranuclear paradesmose between them. The new blepharo- 

 plasts are not at first adherent to the nucleus and traces of faint con- 

 necting fibrils in addition to the paradesmose are found between them 

 and outside, at least in part, of the nuclear membrane (PI. 7, Fig. 83). 

 Later the blepharoplasts become adherent to the poles of the now 

 fusiform nucleus, the paradesmose forms a distinct black line on its 

 periphery from pole to pole, and the faint delicate fibrils between the 

 blepharoplasts become apparently wholly intranuclear (PI. 7, Figs. 85, 

 86). No asters form about the poles. Each blepharoplast is attached 

 to two flagella, the posterior trailing and one anterior flagellum to 

 one, and the other two anterior flagella to the other. Later in the 

 late telophase two new flagella grow out from each blepharoplast (PI. 7, 

 Figs. 91, 92) completing the complement of these organelles. 



The metaphase (PI. 7, Figs. 86-89) brings the chromosomes into the 

 equatorial plate. We have found no evidence here of any precocious 

 longitudinal splitting of the chromosomes prior to their assembling 

 in the equatorial plate. The chromosomes are consistently unlike, 

 There is one large one, one long one, and two subequal medium ones. 

 One of them (Plate 7, Fig. 88) sometimes lags in division. Division 

 in the equatorial plate is by constriction at the middle, that is by trans- 



