ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 691 



Protophyta. 



Distribution of Chromatophores and Nuclei in the Schizo- 

 phyceae.* — Dr. A. Hansgirg describes a new genus of Cyanopbycefe, 

 Chroodactijlon, with the following characters : — Thallus small, hemi- 

 spberical, gelatinous, pale-blue, attached to rocks. Vegetative cells 

 oblong-cylindrical or ellipsoidal, rounded at both ends, united into 

 filiform-cylindrical families more or less irregularly lobed or appa- 

 rently branched ; lobes uniseriate, inclosed in a common colourless 

 gelatinous integument. Cytoplasm homogeneous ; chromatophores 

 distinct, star-shaped, central, inclosing globose pyrenoids. Cell-wall 

 colourless, more or less thickened ; cell-multiplication by successive 

 transverse bipartition, in one direction only. Spores unknown. The 

 typical species, C. Wolleanum, was found on moist siliceous rocks in 

 Bohemia. 



Chroodactijlon is distinguished from most of the blue-green uni- 

 cellular Algse by its distinct cell-nucleus, and by the peculiar form of 

 the chromatophores, which inclose moderately large pyrenoids. Both 

 were stated by Schmitz to be wanting in the Phycochromacese, but 

 have since been found by Schmitz himself, Zopf, and Lagerheim. 



The author claims to have determined that Zopf's Phragnomena 

 sordidum is a true Phycochromacea, and connected genetically with 

 other blue-green algee ; also that Porphyridium cruentum Nag. (Pal- 

 mella cruenta Ag.) is connected in the same way with Lynghya aniliaria 

 Hansg. {Oscillaria antliaria Jiirg.), and is in reality an Aphanocapsa. 

 In both these species are evident nuclei and star-shaped chromato- 

 phores inclosing globular pyrenoids. The reason why they have 

 hitherto generally escaped observation is probably that they are to be 

 found only in the living cell, and not in prepared specimens. 



It is stated by Hansgirg to be a general rule that in the more 

 highly developed PhycochromaceaD, viz. the Lyngbyacese, Calotri- 

 chacese, and Scytonemacese, nuclei, pyrenoids, and chromatophores are 

 not to be found except when they are in a condition of retrogression 

 from the filiform state, and are breaking up into the unicellular 

 condition, 



Chroodadylon is distinguished from its nearest ally among the 

 Phycochromacese, Chroothece, by the formation of cell-families branch- 

 ing in an arborescent manner, and by the star-shaped chromatophores 

 with long rays ; from Synechococcus and Aphanothece by the clearly 

 developed cell-wall of the several vegetative cells and by the forma- 

 tion of a common gelatinous envelope which does not deliquesce. 

 Agreeing with all these genera of Schizophycese in its cells dividing 

 by transverse septa only, it differs from them not only in the peculiar 

 form of the chromatophores, but also in the cells of successive genera- 

 tions being inclosed in a common branched gelatinous envelope. 



With the genus Chroodadylon the author unites Thwaites's Hormo- 

 spora ramosa under the name C. ramoaum. 



Chromatophores with inclosed pyrenoids have been detected by 



* Ber. Dcutsch. Bot. Gesell., iii. (1885) pp. 14-22 (1 pi.). 



