ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 205 



phyceae, arranged under the following headings : — 1. Variation of zoo- 

 spores of certain Chlorophyceee, notably Ulothrix zonata, Stigeoclonium 

 (4 species), Draparnaudia glomerata, Tribonema and Oedogonium. 

 2. Development of zoospores, witli special regard to intermediate forms 

 of swarm-spores. 3. Systematic treatment of Ulotrichales, divided into 

 Tetrakontre and Dikontse. The paper is illustrated with 8 plates, repre- 

 senting the variations by mathematical curves. 



Pathological Growth-phenomenon in Spirogyra and Mougeotia.* 

 Z. Woycicki has investigated further the effect of coal-gas on plants, and 

 adds to our knowledge on the subject. He finds that the quantity of 

 this gas which is present in laboratories exercises a strong influence on 

 the cells of Spirogyra when kept there. Various experiments were carried 

 out on species of Spirogyra and Mougeotia, short accounts of which are 

 given in the present preliminary note, and further details are promised 

 shortly. The results are a further confirmation of the views of Richter. 



Processes of Division, Cell-rejuvenation and Sporulation in 

 Biddulphia.f — P. Bergon gives the results of five years of careful study 

 of the biology of Biddulphia mobiliensis Bailey. Despite prolonged 

 observation he has failed to determine the fate of the motile microspores 

 after their escape from the sporangium. He describes in detail the 

 process of cell-division, the disposition of the nucleus and endochrome 

 in the resting state, the orientation and symmetry of the cell. As regards 

 the formation of auxospores, he finds that in B. mobiliensis they do not 

 arise from the most diminutive cells, but from cells only slightly less 

 than medium size. He therefore prefers to regard this phenomenon as 

 a rejuvenation of the cell, rather than as a method of re-establishing its 

 size. He gives a long and minute description of the details of sporula- 

 tion, which he finds to occur at a fairly constant season in the year, 

 depending, however, rather on the weather. At Arcachon sporulation 

 occurs between the extreme end of December and the end of February ; 

 that is, in the time of greatest vegetative intensity. Fine cold weather 

 is particularly favourable to the process. He thinks that there is a 

 correlation between rejuvenation and sporulation, since he has found 

 the two processes going on side by side in great abundance. He gives 

 a series of measurements of the cell in repose, in rejuvenation, and in 

 sporulation. 



Species of Ceratium in the Gulf of Lyons.J — J. Pavillard publishes 

 notes upon all the species of Ceratium found in the Gulf of Lyons. 

 These are 27 in number, and one of them is new to science. His system 

 is to regard as a species every form that is sharply defined by constant 

 characters, rather than to group them as varieties of a specific type, or as 

 forms of the same variety. In this he follows Schrceder. For some of 

 the species he gives dimensions, which as a rule are invariable. 



Avrainvillea and HalimedaJ — M. A. Howe publishes the third part 

 of his Phycological Studies, and in it he deals almost entirely with the 



* Ber. Deutsch. Bot. Gesell., xxv. (1907) pp. 527-9. 



t Bull. Soc. Bot. France, liv. (1907) pp. 327-58 (4 pis.). 



X Torn, cit., pp. 148-54, 225-31 (1 fig.). 



§ Bull. Torrey Bot. Club, xxxiv. (1907) pp. 491-51G. 



