64 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Fresh-water Algae from Ruwenzori.* — G. B. De Toni and A. Forti 

 have examined the nineteen samples of fresh-water algae collected in 

 the Ruwenzori area by the Duke of the Abruzzi. They record two 

 species and one variety of Myxophycese, two species of Chlorophyceae, 

 and thirty-five species and thirty-four varieties and forms of BaciUarise. 

 Of these, two varieties are new to science. They find a great resemblance 

 between certain of the samples and the flora of El Kab in Upper Egypt, 

 especially in the richness of forms of Rhopalodia gibberula 0. M ., of 

 Navicula sphseroplwra Kutz., and some other species. They also record 

 the widely-distributed Oklamydomonas nivalis Wide from the Duwoni 

 glacier, a fact which helps to confirm the opinion, expressed by Chodat, 

 that the Chlamydomonads of the snow are the most widely-distributed 

 plants in the world. They range from the North to the South Pole, and 

 are probably the pioneers of vegetation in the glacial regions. The 

 species of diatoms recorded from Ruwenzori correspond for the most part 

 with the species designated by Ehrenberg as terrestrial — for instance, 

 Navicula borealis, Hantzschia amphioxys, Melosira Roescana, Navicula 

 mutica f., etc. The authors give a list of the localities whence the 

 samples were obtained, with the predominating character of each, and 

 later give a systematic account of the collection with synonyms, and 

 critical or geographical notes. 



Microspore-formation in Chastoceras Lorenzianum.t — J. Schiller 

 describes the formation of microspores in Chsetoceras Lorenzianum, a 

 plankton-species collected in the Adriatic, where it is fairly common. 

 He gives, first, a short description of the diatom, and states that he 

 has never seen either the resting-spores or the auxospores. The greatest 

 development of 0. Lorenzianum takes place in the autumn, October 

 and November, and to a rather less extent in the late spring and early 

 summer. But the species is remarkable for the irregularity and abrupt- 

 ness of its appearance. It is, however, never entirely absent from the 

 Adriatic plankton. The author describes the method of catching and 

 fixing the material, and then proceeds to give details as to the forma- 

 tion of the microspores in the mother-cell. A mother-spore is first 

 formed, and this divides then into the daughter-spores. The behaviour 

 of the nucleus is not always to be followed out, since the chromato- 

 phores surround it and prevent it from being seen. The author dis- 

 tinguishes two types of microspores, the first being quite round, and 

 varying from 2 '8-3* 3//,. No cilia were visible, and no active move- 

 ment could be observed. The second type had a more oval form, one 

 end being rounded and the other more or less acute. The chromato- 

 phores were distinctly visible, but neither here could cilia or movement 

 be recorded. These microspores vary in size from 5-2 7//. in diameter. 

 The view is taken by the author that these two types represent a sexual 

 differentiation, but, as he says, proof may long be sought for, since the 

 culture of plankton is as yet an unsolved problem. Neither the 

 ripe spores nor the various intermediate stages are provided with a 

 distinct membrane, but each spore is surrounded by a very fine coating of 



* II Ruwenzori, Milano (Hoepli), i. (1909) 31 pp. 



t Ber. Deutsch, Bot. Gesell., xxviii. (1909) pp. 351-61. 



