ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 103 



Heterocystous Nostocaceae.* — MM. E. Bornet and C. Flahault 

 complete their monograph of the Heterocystous Nostocaceee contained 

 in the principal herbaria of France. The fourth and last tribe, the 

 NostocesB, constitute the simplest group, and are divided into the two 

 subtribes Anabeeneae and Aulosirea3. 



The AnabaeneEe are distinguished by the sheath being inconspicuous 

 or dissolving into jelly, or firmer, thick and gelatinous, and are made 

 up of the six genera, Nostoc, Wollea, n. gen., Anahsena, Aphanizomenon, 

 Nodularia, and Cylindrospermum. Under Nostoc are described twenty-nine 

 species, arranged in nine sections; among them is one new species 

 N. maculiforme, found on Enteromorpha intestinalis. The new genus 

 Wollea, belonging to the United States, is founded on Sphserozyga saccata, 

 and is thus described: — Thallus tubulosus, cylindricus, mollis; fila 

 suberecta, paralleliter agglutinata vel leniter curvato-implicata, vaginis 

 confluentibus ; heterocystae intercalares ; sporas catenatas, heterocystis 

 contigusB vel ab eis remotae. Anahsena includes eleven species, divided 

 among the three sections, Trichormus, Dolichospermum, and SpJiserozyga. 

 Two new species, A. sphserica and laxa, are described. Aphanizomenon 

 includes only two species, and Nodularia four, one of the latter, N. 

 sphserocarpa, being new. Under Cylindrospermum are enumerated five 

 species. 



The subtribe Aulosireae is characterized by the filaments having 

 a thin membranaceous sheath, and being free or agglutinated into 

 parallel bundles. It is made up of the genera Aulosira with two 

 species, and Hormothamnion Griin. also with two, one of them, H. 

 solutum, being new. 



As an appendix is added the subtribe Isocysteae of Borzi, made up 

 of the single species Isocystis Messanensis Borz. The subtribe differs 

 from the typical Nostocege by the absence of heterocysts, and is thus 

 characterized : — Trichomata cellulis perdurantibus (heterocystis) desti- 

 tuta, muco parcissimo involuta, in thallum irregulariter diffusum 

 densissime aggregata, raro subsolitaria. 



Relationship of Bacillus muralis and Glaucothrix gracillima.t — 

 Prof. H. Tomaschek adduces further arguments ''against the view of 

 Hansgirg | that there is a genetic connection between these two organ- 

 isms, and that' of Zukal § that the Schizomycetes are descended from 

 the Schizophyceae. 



He regards Bacillus muralis as an endosporous and not an arthro- 

 sporous bacterium (in de Bary's sense), and therefore characterized by 

 the production of aplanospores, while in the Phycochromaceae only 

 akinetes are formed. The objection that B. muralis is not a true 

 bacterium, founded on its immotility, is also not conclusive, since the 

 same objection would apply to B. anthracis. Equally inconclusive is 

 the objection that B. muralis is invested with a gelatinous envelope, 

 since this also holds good of some undoubted bacteria, such as Bacterium 

 cyanogenum, and of Beggiatoa. 



Prof. Tomaschek has found intermixed with Bacillus muralis^ true 

 zoogloea-colonies of Glaucothrix gracillima or Aphanothece caldariorum, 



* Ann. Sci. Nat. (Bot.), vii. (1888) pp. 177-26. Cf. this Journal, 1888, p. 472. 

 t Bot. Centralbl., xxxvi. (1888) pp. 180 (figs. 2-6). Cf. this Journal, 1888, 

 p. 786. 



t See this Journal, 1888, p. 787. § Ibid., 1884, p. 601. 



