14S SUMMARY OF CUKKENT KESEAKCHES KELATING TO 



he completes his treatment of Liagora, and discusses fully the species 

 of Chtetangiaceffi, Gelidiacete, Wrangeliaceffi and CTrateloupiacese. 

 Rhizophyllidacege are treated by Madame Weber van Bosse. New 

 species are described and figured by each of the authors. 



Sexual Organs of Laminaria.* — C. Sauvageau describes the game- 

 tophytes of Laminaria, wliich he has discovered. In a previous paper 

 he described similar organs for Succor hiza. His account is as follows : — 

 Whatever may be the sex of the future prothallus, the embryospore of 

 Laminaria ffexiccmlis and L. saccliarina retains its diameter of about 5 /x. 

 After the first or second day following dehiscence, the chromatophore 

 having doubled itself, a \'ery narrow tube (less than 2 /x,), regular or 

 varicose, is emitted, the extreme end of which swells up and receives 

 the major part of the contents. The entire growth resembles a dumb- 

 bell. The orientation of this germinating tube is independent of the 

 direction of light, and seems to be determined by the position that the 

 protoplasm of the beak of the zoospore occupies in the embryospore. 

 The nucleus remains in the background, in the tube, or more often in 

 the embryospore, and divides. One of the daughter-nucki passes into 

 the swollen portion, which is then cut off by a transverse wall, and 

 it becomes the origin of the piothallus, Avhilst the other becomes 

 disorganized. It would seem that the nucleus of the zoospore had to 

 undergo sub-division in order to acquire the sexual character. The 

 empty embryospore slowly detaches itself from the prothallus by 

 destruction of the tulje. Sometimes, however, the migration is 

 incomplete ; the posterior nucleus does not die and the embryospore is 

 added to the gametophyte. The swollen extremity continues to increase, 

 and multiplies its chromatophores. Certain male prothallia are of a 

 precocious nature ; they are minute, and gradually become covered with 

 antheridia. Others become bushy, compo^:ed of creeping filaments, 

 either producing sessile antheridia or emitting from most of its cells one 

 or two erect fertile branches ; some of them throw out about fifty 

 branchlets. The different forms occur in the same culture. The 

 antheridia are lateral and more or less tubular, or intercalary ; 

 uninucleate and almost colourless, they contain nevertheless one or two 

 chromatopliores much reduced and very pale. At the moment of 

 maturity their membrane swells on the inner side of the beak and 

 compresses the contents ; then this cork-like body is dissolved for the 

 dehiscence. In a culture, the antherozoids are always liberated before 

 any female prothallus has began to produce oogonia ; they are there- 

 fore useless, but, in a natural condition, this protandry is favourable 

 to fecundation ; besides, the male prothallia remain fertile for a long 

 time and the zoospores are emitted in great quantity, and the prothallia 

 are contiguous and entangled. 



The swollen extremity which becomes a female prothallus grows for 

 a longer time. Sometimes it is transformed into an oogonium without 

 previous division, and the nucleus of the oosphere is then a half-nucleus 



* C.R. Acad. Sci. Paris, clxii. (1916) pp. 601-4 (figs). 



