ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 525 



Kuckuck, the Fresh- water Algaa by E. Lemmermann, the Bacillariales 

 by B. Schroder, and the Peridiniales by E. Lemmermann. The names 

 of the species are given in alphabetical order and are divided into two 

 groups : those new to the district and those worthy of note. The 

 locality of each species is given, and each list is preceded by an enumera- 

 tion of literature bearing on the subject. 



Morphology and Physiology of Scenedesmus acutus.* — J. Grint-_ 

 zesco has made a series of experiments on this alga and comes to 

 the following conclusions. The two principal conditions in which it 

 may exist are the Ccenobium and Dactylococcus state, in the latter of 

 which the cells are either free or joined together in chains. The alga 

 flourishes equally well on agar-agar as on gelatin, which latter medium it 

 liquefies. Glucose tends to hasten development for a time only. The 

 alga shows marked polymorphism, especially under certain conditions, 

 and protococcoid forms are often seen in cultures on dishes of porous 

 porcelain. The alga may develop in the dark, but not so speedily as in 

 light. It can also grow in a vacuum, and its limits of temperature may 

 vary from 2°-30°, the optimum lying between 18° and 20°. 



Structure and Life-History of Diatoms.f — F. R. Rowley gives a 

 full abstract of work published by Lauterborn in 1896, on the proto- 

 plasm, nucleus, centrosome, and phenomena attending nuclear and cell 

 division in diatoms. Species of Surirella, Nitzschia, Pleurosigma, Pinnu- 

 laria, Navicula, &c. were studied. Pfitzer's results concerning the 

 arrangement of the protoplasm were in the main confirmed, and many 

 bodies, previously regarded as oil-drops, were found to be the " red 

 granules " of Biitschli. The protoplasm was shown under high magnifi- 

 cation to be distinctly reticulated, not granular. Short, paired, rod- 

 like bodies (" Doppelstiibclmi ") were seen in certain Pinnularm to be 

 connected with a plexus of anastomosing fibrils situated between the 

 chromatophore and the cell-membranes, and at the beginning of nuclear 

 division these rods and fibrils exhibit a radial arrangement with respect 

 to the nucleus. In Surirella an irregular anastomosing system of fibrils 

 has been observed, but the paired rods of Pinnularia have not been 

 seen in Surirella except in the initial stage of nuclear division. Some 

 of the fibrils possess the power of independent movement. Similar 

 structures have been observed also in Bryojjsis and Spirogyra. 



Chromatophores and pyrenoids are dealt with, and methods are given 

 for showing the difference between oil-drops and " red granules." The 

 paper closes with an account of the various stages of mitosis in Surirella 

 calcarata, which Lauterborn regards as a model for other species in the 

 matter of cell-division. Lauterborn holds that diatoms multiply by 

 division rather than by spore- formation, since among the thousands of 

 examples he has examined no trace of spore-formation was observed, 

 while he saw and studied hundreds of dividing cells. This paper is 

 illustrated by 13 figures, 5 of which are in the text. 



Fossil Diatoms of Auvergne.J — F. Heribaud gives a list of 160 

 species of fossil diatoms collected from deposits in various parts of 



* Bull. Herb. Boiss., ser. 2, ii. (1902) pp. 217-64, 400-29 (5 pis. and 6 figs.) 

 Hedwigia, xlii. (1903) Beibl., p. 124. 



t Journ. Quek. Micr. Club. viii. (190?,) pp. 417-30 (pi. 23 and 5 figs, in text). 

 X 'Les Diatome'es fossiles d'Auvergne,' Paris, 1902, pp. 79 (2 pis.). 



Aug. 19th, 1903 2 m 



