502 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Formation and fusion of the gametes was induced by the addition of a 

 •_' p.c. sugar solution to the culture. The gametes arose in colonies of 

 sixteen, of small size, one from each mother-cell. When the gametes 

 are ripe, they become free from the enveloping gelatinous sheath. The 

 structure resembles in the main that of the ordinary cells. They are 

 small, bare, and pyriform. After the gametes have swarmed for about 

 an hour, they begin to copulate, sometimes showing marked disinclina- 

 tion or inclination towards a special gamete. The process is described 

 in detail. The zygote rounds itself off, and in the course of a few hours 

 develops a thick membrane, which is not, as Chodat states, wrinkled. The 

 author allowed these hypnospores to remain dry for about eight to ten 

 days and then moistened them, whereupon after a few days they began 

 to germinate. Cell-division takes place and four microspores are formed. 

 These when ejected are bare, at first without cilia, hanging together and 

 passively motile. The connexion is probably caused by gelatinous matter. 

 The ejection is caused by mechanical pressure. After a time the spores 

 develop two cilia, and begin to move about in the water. Their further 

 course is not known. This account of the formation of gametes differs 

 greatly from that given previously by Chodat. Finally, the author gives 

 details of the growth of the cilia, which have never been properly de- 

 scribed, and adds remarks on certain abnormal growths similar to those 

 already observed and described by Migula. 



New Sp&cies of Debarya.* — S. R. Price describes and figures a new 

 species of Debarya, collected from stagnant ponds on Sheep's Green, 

 Cambridge. Specimens were transferred to algal culture tubs, where 

 conjugation was observed. The process is Very similar to that described 

 for D. desmidioides and D. Hardyi. The author points out that Debarya 

 may be regarded as a form from which two lines of evolution diverge, 

 the one leading to the Mesocarpacese, and the other to the Desmidiaceas. 



Pleodorina californica.t — E. Chatton publishes an exhaustive ac- 

 count of Pleodorina californica Shaw, which he has found and studied at 

 Banyuls-sur-mer. Other authors describe the appearance of this alga 

 in June, but Chatton records it as occurring at the end of April at 

 Banyuls He has succeeded in cultivating the alga and watching the 

 process of reproduction, which he describes for the first time. A mor- 

 phological study then follows. The rest of the paper is devoted to some 

 cytological observations, remarks on the systematic position of P. cali- 

 fornica, and finally some general reflections. 



Corroding Alga.J — W. Bialosuknia has made some interesting re- 

 searches on Diplosphsera Chodati Bial., a pleurococcus alga isolated from 

 a lichen from the limestone of Saleve, viz. Lecanora tartarea Ach. Ex- 

 periments on this alga have shown that it possesses a power of corroding 

 the limestone rocks, and that this action is not the result of an organic 

 acid, but of a carbonic acid. The experiments are described in detail, 

 and similar work of other authors on other plants is discussed. 



* New Phytologist, x. (1911) pp. 87-9 (1 pi.). 



t Bull. Sci. France et Belgique, ser. 7, xliv. (1911) pp. 309-34. 



t Bull. Soc. Bot. Geneve, ser. 2, iii. (1911) pp. 6, 13-18 (figs.). 



