508 SUMMARY OF CURRENT RESEARCHES RELATING TO 



the intervals between the liberation of the the two species was tolerably 

 constant. In other species of Sargassum too, the same held good. He 

 concludes, therefore, that the liberation of oogonia in Sargassum and 

 GystopliyJlum takes place periodically and simultaneously among individ- 

 vals of the same species growing in the same locality ; but the intervals 

 between two successive liberations vary in an irregular manner, without 

 having at least any fixed relation to the highest spring tide. The 

 author describes the mode of oogonium liberation in S. Horneri. The 

 paraph yses do not protrude from the conceptacle as in Fucus, but com- 

 pose a disk-like plug at its opening. In a few seconds after immersion 

 in the medium, in which the author watched the process, the plug came 

 out slowly with some broken pieces of paraphyses on its inner surface ; 

 and then the conceptacle began to discharge its oogonia one after another. 

 The further progress is described. The mode of liberation in Cgsto- 

 phyllum sisgmbrioides differs considerably from that of S. Horneri, and 

 is also here described. The author next discusses the early stages of 

 embryogeny. He finds that the view generally held is correct, namely, 

 that three successive nuclear divisions in the oogonium take place before 

 the formation of oospheres, and that Sargassum is no exception to the 

 rule, as was held by one author. The process is described and figured. 

 Spermatozoids were not observed. The development of the sporelings 

 is described for Sargassiim and Cystophylhim. The author's results do 

 not agree with those of Nienburg as to the segmentation of the 

 oospheres. 



Antarctic Melobesiese.* — Madame Lemoine publishes an important 

 report on Antarctic Melobesieag, founded primarily on the collection 

 brought home by the second Charcot Expedition (1908-1910). For 

 the proper estimate of the species contained therein, the author found 

 it necessary to study the collections of all the other Antarctic expedi- 

 tions of later times, and the result is the valuable monograph now 

 published. She divides the area into three regions : 1. South Atlantic 

 or South American. 2. South Australian. 3. South Indian. Then 

 follow a list of the species recorded from each, and a revision of the 

 genera represented. Lithothamnium is divided into three groups, 

 founded on structural differences, and the different species of each 

 group are treated in detail. Synonymy is given and details of structure 

 are figured. One new species, L. Mangini, is described. The genus 

 Lithophyllvm is divided into four sub-sections, the first three of which 

 are represented in the Antarctic regions by one species only, L. rugosum, 

 and that species is regarded by the author as a transition between Liiho- 

 thamniam and Lithophylhim. The genus Lithojyhyllum is represented 

 indeed in the Antarctic only by species aberrant from the structural 

 point of view. A new sub-genus, Antarcficophyllum, is founded on 

 characters of the hypothallus, and includes two species. Pseudolitho- 

 phyUum, a new genus, includes also two species formerly belonging to 

 Lithophyllum. Under General Considerations the author treats of the 

 Results of the Charcot Mission, the Geographical Distribution of the 



* Deux. Exped. Antarct. Fran^aise (1908-10) Charcot Sci. Nat. : Melobesi6e.s. 

 Paris : Masson (1913) 67 pp. (2 pis. and figs, in text). 



