ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 567 



Classification of Cyanophycese.* — Dr. A. Hansgirg supplements his 

 scheme of classification of the Myxophyceaa (Cjanophycca3) by a few 

 additional details, and adds descriptions of a new species Cyanoderma 

 (Myxoderma) rivulare. 



Parasitism of Nostocf — In reference to the observations of Frank J 

 on the power of plants to absorb free nitrogen from the atmosphere, 

 Prof. K. Prantl suggests that this may be the function of the colonies of 

 Nostoc or Anabaena so frequently found in cavities in the leaves of 

 Blasia, Anthoceros, Azolla, Gimnera, Cycas, &c., thus serving to helj) in 

 the nutrition of the host-plant. The same also may be the purpose of 

 the Schizophycese belonging to these genera which enter into the 

 composition of Collema and other large lichens. 



)3. Schizomycetes. 



Morphology and Physiology of the Sulphur Bacteria.§— The first 

 volume of his work on Bacteria Dr. T. Winogradsky devotes to the 

 Sulphur-bacteria. 



In a short introduction the author discusses the views of Eay 

 Lankester, Warming, Zopf, and Cohn, who have expressed opinions for 

 or against the pleomorphism of these organisms. After reviewing the 

 various sulphur-bacteria, he decides that all the forms are distinct 

 species, and are not pleomorphic organisms, and that all the forms 

 included by Lankester, Zopf, and Warming can be sLarply separated 

 from one another. 



Thus Gladothrix dichotoma developes in quite a simple manner ; the 

 spirilla, zoogloeae, &c., which Zopf has connected together are indepen- 

 dent organisms ; and this is the case with leptothrix and others. In con- 

 clusion, the author shows that the last support of the doctrine of 

 pleomorphism has been removed, and that Cohn's classification of the 

 species was correct. 



Prof. A. Hansgirg, |1 on the other hand, regards the sulphur-bacteria 

 described by Winogradsky as forms, developed under special con- 

 ditions, of already known genera and species. At all events, as far 

 as the genera are concerned, he identifies Winogradsky's Thiotrix with 

 Borzi's Ophryothrix, TMosarcina with Sarcina, Thiopedia with Lampro- 

 pedia, and Thiospirillum with Spirillum. Thiopolycoccus, Thiocapsa, and 

 Thiocystis must also probably be sunk in corresponding genera pre- 

 viously described. 



Bacteria which produce Sulphuretted Hydrogen. f— Dr. Holschew- 

 nikoff, in a somewhat diffuse paper on the formation of HoS by bacteria, 

 gives the result of a few experiments made with two bacteria, called 

 Proteus sulphureus and Bacterium sulphureum. 



The former appears to closely resemble Proteus vulgaris Hauser, 

 even if it be not identical with it. The latter, which was isolated from 

 some reservoir mud, consists of rodlets with rounded ends, and with 

 a length of 1 • 6-2 • 4 /x, and breadth of • 5 /a. In the former aerobic 



* Notarisia, iv. (1889) pp. 656-8. Cf. this Journal, ante, p. 102. 

 t Hedwigia, xxviii. (1889) pp. 135-6. J Cf. this Juurnal, ante, p. 412. 



§ ' iSeitrage zur Morphologie und Physiologie der Bacterien,' 8vo, vol. i Leipzig- 

 1888, vi. and 120 pp., 4 pis. Cf. this Journal, 1887, p 1007 ' i &> 



II Bot. Centralbl., xxxvii. (1889) pp. 413-4. 

 ^ Ann. de Micrographie, ii. (1889) pp. 257-74. 



