82 SYNGAMY IN PROTOZOA 



filament provided with a head, while the stationary one retains its original 

 form (Fig. 46). This observation is a confirmation of the view that the 

 migratory nuclei in other ciliates are actually male nuclei. 



GONOMERY. — A remarkable process of syngamy was described by 

 Hartmann and Nagler (1908) for Sappinia diploidea, an amoeba isolated 

 from lizards' faeces. The amoeba is peculiar in being binucleate, the 

 two nuclei lying close together (Fig. 47). When encystment occurs, two 

 individuals enter a common cyst. The two nuclei of each individual now^ 

 fuse and then undergo reduction divisions, the reduction bodies degenerat- 

 ing. After this the two amcebse unite, the nuclei approach one another, 

 but do not fuse. The amrrbn then leaves the cyst and commences to 



d e f 



Fig. 47. — Sapjyinia dij)loidea : Fkee and Encysted Stages ( x ca. 1.500). (After 

 Hartmann and Nagler, 1908.) 



a. Usual form with two nuclei. I. Form with dividing nuclei. 



c. Dividing form producing two binucleated daughter amcebse. 



d. Two amcebse in common cyst. e. The two nuclei in each amoeba have united. 



/. The bodies of the two amoebae have fused, giving rise to a binucleated amoeba which escapes 

 from the cyst and reproduces by binary fission, as at n, h, and c. 



multiply by binary fission, the two nuclei dividing by mitosis side by side. 

 These nuclei are regarded as gamete nuclei, which, however, do not actually 

 unite, though dividing many times during asexual reproduction till 

 encystment again occurs. This condition is one of delayed union of gamete 

 nuclei, a process which is known to occur in higher animals, and which has 

 been teTmed gono7nery. 



METHOD OF UNION OF GAMETES.— The actual union of gametes 

 during syngamy takes place in a variety of ways, which are dependent on 

 the structure of the gametes themselves. In the case oi Polytoma uveUa, 

 Copromonas subtilis, and other forms, the two flagellates approach one 



