ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 211 



Bryophyta. 

 (By A. Gepp.) 



Sporogenesis of Sphagnum squarrosum.* — E. Melin describes the 

 sporogenesis of Sphagnum squarrosum Pers., and adds remarks on the 

 antheridium of S. acuUfolium. The work is divided into four 

 chapters :— 1. The sporogenesis of *S'. squarrosum'. 2. The chromato- 

 phoresof Sphagmwi. 3. Remarks on the antheridium of S. acutifolium. 

 4. The systematic position of SpTia.gn.um. In the first chapter the 

 nuclear division of S. squarrosum is minutely described. In the second 

 the author discusses the behaviour of the chromatophores of the 

 sporophyte. The cells of the young sporophyte contain, like the 

 egg-cell, several chromatophores. In the young archespore, however, 

 they do not appear to divide, but distribute themselves among the 

 daughter-cells, so that in each archespore there is finally only one 

 chromatophore. The sterile sporophyte-cells on the other hand have 

 always several chromatophores. In the spore-mother-cells the number 

 increases from one to four, and each of the four young spores receives 

 one. This fact is considered by the author as one of great systematic 

 importance. As regards the antheridium (chapter III.) the first 

 divisions take place as Leitgeb describes. A two-edged apical cell is 

 formed. The divergence of the cells is not however one-half, but much 

 smaller. Each segment is, like the Muscinese and the Jungermanniales, 

 divided into three cells by two walls having a chord-like course, one 

 outer and one inner. The androcyte mother-cells are elongate-elHpsoidal, 

 as in mosses, and their spindles are orientated in their lengthwise 

 direction. In the cytoplasm of the androcyte mother-cells there appear 

 two bodies, highly stainal:)le, of which there was no trace in the 

 preceding mitoses. The author calls them " Blepharoplasten," since 

 they are in his estimation identical with the cilia-forming bodies 

 occurring in the androcytes. 



As regards the systematic position of Sphagnum, the author is of 

 the opinion that it is a true moss, and has been developed from a 

 moss-like type. The behaviour of the chromatophores, the development 

 of the antheridia, the form of the androcyte mother-cells, and the 

 lengthwise orientation of the nuclear spindles all point to this 

 conclusion. He believes that Sphagnum is a moss which in some way 

 was adapted to meet periodic xerophil conditions, and lack of nutrition 

 on moorland country. In which group the nearest relatives are to be 

 sought is still a question. 



Structure of Aytonia.f — Anna M. Starr gives an account of the 

 structure of a Mexican species of Aytonia { = Plagiochasma) . In 

 summing up the results of her investigation of this hepatic, she says 

 that : — 1. Two appendages may be present on the ventral scales. 

 2. Rhizoids are absent among the first pairs of ventral scales. 3. Old 



* Svensk. Bot. Tidskr. ix. (1915) pp. 261-93 (1 pi. and figs.). See also Bot. 

 Centralbl., cxxix. (1915) pp. 672-4. 



t Bot. Gaz., Ixi. (1916) pp. 48-58 (4 pis. and figs.). 



