Oogonium Liljeration and the Emljryogeny of Some Fucaceous Algae. 5 



month's culture the branches Kberated the oogonia in a very 

 feeble manner. 



I often observed the actual mode of oogonium liberation in 

 Sargassimi and Cijstoplujllum in common sea-water under the micro- 

 scope. But when I collected some small l)ranches on the day 

 before the day of an oogonium liberation and put them into a 

 mixture of sea-water and fresh water (one volume of sea-water to 

 four of fresh water proved to be the best proportion). I could 

 quite easily observe the mode of the oogonium liberation. I 

 studied the mode of oogonium liberation in S. Hörnen more 

 minutely than in other species, and the following description refer 

 to this plant. 



Generally speaking, the paraphyses of Sargassum do not 

 protrude from the conceptacle as they do in Fucm. In 5'. Horneri 

 they compose a disklike plug at the opening of the conceptacle. 

 In a fcAv seconds after immersion in the mixtui'e medium above 

 mentioned, the plug comes out slowly, with some broken pieces 

 of paraphyses on its inner surface (Text. Fig. 1); and then the 



conceptacle commences to discharge 

 its oogonia one after another. The 

 discharged oogonium has a thick 

 outer layer of gelatinous substauce, 

 which trails out a tail fastened to 

 the interior of the conceptacle 

 (Text Fig. 1). In one or two days 

 the gelatinous substance becomes 

 less rigid and the tail can no more 

 be recognized with certainty, but 

 still for a time the discharged oogo- 

 nium remains attached to the recep- 

 tacle. 



As already stated in my preliminary note, the oogonia in one 

 receptacle are not liberated at one time, but in succession, one 

 zone after another in acropetal order. Fig. 1 of Plate I shows the 



Fig. I. X 140 



