106 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 3 



comes strongly amoeboid. Its contents become watery and spread over 

 the oogonial apex (pi. 16, figs. 1-4). Numerous small vacuoles appear 

 and disappear so rapidly as to give an appearance of cytoplasmic "boil- 

 ing." The cilium waves feebly above the body of the sperm and, as the 

 cytoplasm of the male gamete gradually sinks into the ooplasm, becomes 

 more hyaline in appearance. During absorption of the male gamete the 

 ooplasm expands and for a short time fills the oogonium (pi. 16, figs. 5, 

 6). In none of the many cases of fertilization observed was the body of 

 the male gamete completely engulfed by the ooplasm. There always re- 

 mained a small, papillalike part at the apex, from which protruded the 

 cilium of the antherozoid (pi. 16, fig. 6). The remainder of the male 

 gamete could be detected for a time as a more slightly granular material in 

 the anterior part of the egg, but it was soon lost to view. Almost instantly 

 after the absorption of the major part of the antherozoid, the papillalike 

 residue of this structure on the surface of the egg started to increase in 

 size (pi. 16, fig. 7). This marked the initiation of evacuation of the 

 zygote from the oogonium. More definite evidence of emergence could 

 then be seen in the migration of the large, conspicuous globules into the 

 enlarging papilla (pi. 16, figs. 8-10). These continued to flow out with 

 the cytoplasm of the zygote. Meanwhile, the cilium remained passive 

 and, as the zygote continued to ooze out, slowly assumed a lateral posi- 

 tion with respect to the orifice of the oogonium. The completely emerged 

 zygote was at first somewhat pyriform, with the cilium nearly basal and 

 extending at a right angle or more to the long axis of the body (pi. 16, 

 fig. 11). It then rounded off (pi. 16, fig. 12), remained quiescent for a 

 few seconds, and then began to rock gently. A trembling movement of 

 increasing intensity was soon initiated, which frequently carried it away 

 somewhat from the oogonial orifice (pi. 17, fig. 1). Lateral vibration of 

 the hitherto quiescent cilium then occurred, and vacuoles appeared in the 

 anterior part of the now more ovoid body (pi. 17, fig. 2). After a few 

 violent tugs, accompanied by rapid vibration of the dark-appearing 

 cilium, rotation of the zygote on its long axis as well as forward pro- 

 gression was initiated, and it slowly swam ofi. Under poor environmental 

 conditions the zygote may fail to emerge, and the oospore is formed in 

 the oogonium (pi. 17, fig. 7). 



After a period of motility of unknown duration, frequently punctu- 

 ated by periods of quiescence and strong amoeboid crawling (pi. 17, fig. 

 3), the zygote comes to rest. Its cilium is apparently absorbed (pi. 17, 

 fig. 4), and the body becomes surrounded by a thickened wall (pi. 17, 



