Cytology of a new variety of A chlya americana . 1 79 
Fig. 43. Median section of a small oogonium producing two eggs at the stage 
represented in Fig. 12. The young egg represented in median section is uni- 
nucleate, and the nucleus is surrounded by kinoplasm with fibrous structure, x 1,200. 
Fig. 44. Section of an oogonium with two unfertilized eggs, the right-hand egg 
with a single nucleus ; the nucleus of the left-hand egg was in the next section. 
An antheridium has produced a germ-tube, and a male gameto-nucleus may be 
seen in it near its apex, x 1,200. 
Fig. 45. Section of an oogonium with four eggs, two of which are represented 
in outline only. The lower egg has a central female gameto-nucleus in which 
there is no nucleolus ; the upper egg has a similar central female gameto-nueleus, 
and a peripheral male gameto-nucleus at the apex of the fertilization-tube which 
lies within the egg. x 1,200. 
Fig. 46. Section of an oogonium with three binucleate oospores, the female 
gameto-nucleus of the upper one, however, was in the next section. The central 
nucleus is provided with a small nucleolus, x 1,200. 
Fig. 47. Portion of a section of an oogonium from a five-day culture with three 
binucleate oospores, a part of one of which is represented in outline only. The 
gameto-nuclei are in close juxtaposition, x 1,200. 
Fig. 48. Portion of a section of an oogonium from an eight-day culture with 
four binucleate oospores ; the nuclei in the resting condition, and suggesting an 
approaching fusion, x 1,200. 
Fig. 49. A single uninucleate oospore from an eight-day culture. There are 
indications of an incomplete fusion, x 1,200. 
Fig. 50. Part of a section of an oogonium from an eight-day culture with 
uninucleate oospores, x 1,200. 
Fig. 51. Uninucleate oospore from a nine-day culture, x 1,200. 
Fig. 52-59. Successive stages in the germination of the oospores, x 1,200. 
Figs. 60-70. Nuclear figures from the germinating oospores. They all refer to 
the later divisions, being taken from oospores with at least eight nuclei, x 2,400. 
