634 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Grun. as a variety of M. crenulata and suggests it be called M. ambigua 

 (Grim.). The sub-species with mixed pores he would call M. variata, 

 and that with fine pores M. jnincticulosa. 



Cyclotella bodanica var. lemanica.* — H. Bachmann has made a 

 special stncly of this diatom from specimens collected by him in the 

 Lake of Lucerne, where it may be found all the year round. He 

 describes the methods of collecting the material, which he studied in the 

 fresh condition, though he was unable to cultivate it himself. A 

 description of the genus Cyclotella is given, describing minutely the 

 various external and internal characteristics. The species studied 

 was never found in colonies. Tables then follow which show the 

 seasonal occurrence at different heights in different parts of the lake, 

 illustrated by a small map and by two diagrams (charts ?). The rest of 

 the paper is devoted to the subject of the reproduction of Cyclotella, 

 (1) by cell-division ; and (2) by the formation of auxospores. Cell- 

 division is always preceded by the division of the nucleus. As regards 

 the type of auxospore formation, the author finds that it comes under 

 the fourth of Karsten's classes, like most plankton-diatoms, of which 

 the characteristic is that " An auxospore arises from one mother-cell by 

 suppressed division." The author has often followed the formation of 

 the auxospore in its early condition and describes the process in detail. 

 He finds that auxospores occur most frequently in Cyclotella lemanica in 

 November and December, lasting on into May and being entirely 

 wanting in the summer ; and since this form of reproduction is largely 

 dependent on outward influences, he presumes that in the case of this 

 diatom their appearance is connected with change of temperature. The 

 impulse towards the formation of auxospores is given by the protoplasm, 

 not by the nucleus. 



Diatoms of Auvergne.f — J. Heribaud collects together all the 

 records he has made since 1898 up to the present time of the diatoms of 

 Auvergne, and arranges them according to the classification of the raphe, 

 following in the main the lines of Van Heurck, but slightly modified by 

 the work of Cleve and Peragallo. He enumerates 908 forms, of which 

 5G4 are species and 344 varieties : 281 are new. In the tertiary 

 deposits of the upper Loire and of Ardeche the author finds 37 forms, 

 mostly new to science. 



Diatoms of the Atlantic. J — G. Murray publishes some notes on 

 Diatornacese collected by the pumping method, principally by himself 

 and Y. H. Blackman, during a voyage to the West Indies in 1897, and in 

 subsequent voyages by other collectors in the same year. It was found 

 that a small number of species occur constantly, but sparsely, in the 

 open ocean, varying with the temperature. As land was approached the 

 diatom-flora increased in quantity and variety, showing its coastal 

 character. A series of collections made in the warm waters near Colon 

 from July to December is noteworthy for the richness and constancy of 

 its diatom-flora. The samples were submitted to T. Comber for deter- 



* Jahrb. wiss. Bot., xxxix. (1903) pp. 106-31. 



t Disposition me'th. d. Diatomees d'Auvergne, Klinksieck, 1903. See also Nuov. 

 Notar., xiv. (1903) p. 122. % Journ. Bot., xli. (1903) pp. 275-77. 



