■64 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Van Heurck. Synonymy is excluded save in so far as it is necessary 

 for keeping in touch with Norman's lists. Attention is called, in the 

 introduction, to the fixity of certain species in certain localities, and, on 

 the other hand, to the appearance or disappearance of other species in 

 other places, for reasons at present unknown. Norman's slides have 

 been submitted to re-examination. 



Licmosphenia, a New Genus of Diatoms.* — C. Mereschkowsky 

 founds his new genus Licmosphenia on diatoms collected at Villefranche, 

 •and places in it five species — L. Grunouii, L. Clevei, L. Peragalli, 

 L. Schmidtii, and L. Van Heurckii. He gives a full description and 

 figures of each species. The genus is intermediate between Licmophora 

 and Climacosphenia, from which it differs in the disposition and per- 

 forations of the septa. In Licmophora the septa are perforated by a 

 single large orifice ; in Climacosphenia there are several such orifices, 

 and in Licmosphenia there are two only. The paper ends with a key to 

 the species. 



Reproduction of Valonia.f — P. Kuckuck gives a short preliminary 

 account of the mode of reproduction in Valonia ovalis. Several days 

 before the spores are ripe and ready to escape, certain delicate markings 

 become visible on the wall of the mother-cell, and dark-green agglome- 

 rations of protoplasm are found in the shape of rings or branched 

 bands. The cell-membrane covering this portion of the mother-cell 

 then develops thin spots, around which the masses of protoplasm 

 gradually split up (serlcluften), the membrane breaks, and the zoospores 

 escape. The posterior end of the zoospore is deeply coloured and full 

 of starch, the anterior portion being colourless and having two cilia. 

 No eye-spot was to be seen, and the zoospores did not unite in pairs. 

 After a time the mother-cell resumes its normal colour, the openings 

 close up, and eventually the process of reproduction is repeated. It is 

 remarkable that the zoospore is not divided off from the surrounding 

 protoplasm by any cell-wall ; and since the contents of the mother-cell 

 are at the time of the escape of the zoospores in direct contact with the 

 outer world, considerable firmness of the membrane is necessary to pre- 

 vent collapse of the entire cell. 



New Genus of SiphoneaB.J — A. Ernst founds a new genus, Dicho- 

 tomosiphon, for the reception of the alga which till now has been 

 known as Vaucheria tuber osa A. Braun. His paper on the subject is 

 divided into (i.) Vegetative Organs ; (ii.) Reproduction ; (iii.) Syste- 

 matic Position of Dichotomosiphon. Under the first heading the branch- 

 ing is described as beginning in a dichotomous manner, and ending as 

 tri- or sometimes penta-chotomous. The cell-membrane and cell-con- 

 tents, including chlorophyll- and starch-grains, are treated in detail, and 

 the similarity is pointed out which exists between this genus and 

 Codiacese. Under Reproduction are described the oogonia and an- 

 theridia, which arise terminally on short special branches. The develop- 

 ment of each has been traced, and is here described, together with an. 



* La Nuova Notarisia, 1902, pp. 177-83 (5 figs, in text). 

 t Ber. Deutsch. Bot. Gesell., vii. (1902) pp. 355-7. 

 X Beih. Bot. Centralbl., xiii. (1902) pp. 115-48 (5 pis.). 



