250 Bryophyten. — Pteridophyten. 



Frye, T. C, The Polytrichaceae of Western North America. 

 (Proc. Washington Acad. Sei. XII. p. 271— 328.textfig. 1—30 August 

 15, 1910.) 



Ot" the 10 genera of mosses comprising the family Polytrichaceae 

 7 are represented in western North America, by 27 species. 

 These are described and elaborately illustrated by text figures in 

 the present paper. One new "combination" apears: Oligotrichum 

 incurvum latifoliuni {Oligotrichum hercynicum latifolium C Müll, 

 and Kindb.). Maxon. 



Beer, R., Studies in Spore Development. III. The Pre- 

 meiotic and Meiotic Nuclear Divisions of Equisetum 

 arvense. (Ann. Bot. XXVII. 108. p. 643—659. pl. 51—53. 1913.) 



The author of this paper published a preliminary account of 

 the development of the spores of Equisetum in 1909 (New Phytol. 

 Vol. VIII, p. 261). Since that time E. Hannig has made a detailed 

 study of the same subject and has confirmed the author's results 

 regarding the origin of the much disputed "middle coat" of the 

 Spore wall. As this is the case, the author considers it unnecessary 

 to publish his results upon the spore wall in greater detail, and 

 contines himself in the present paper to the nuclear divisions asso- 

 ciated with spore development which were not dealt with by 

 Hannig in his memoir. 



The raore important of the conclusions reached may be indi- 

 cated very briefly as follows: 



In the premeiotic divisions a spireme which is discontinuous 

 from the first is developed from the nuclear reticulum by the gra- 

 dual withdrawal of branches and anastomotic connexions. In the 

 process of formation of the daughter nuclei the chromosomes open 

 out and their substance becomes distributed along numerous bran- 

 ches which develop between them. It appears to be entirely by 

 these means and without any indications of internal vacuolisation 

 that the reticulum of the resting nucleus develops from the chro- 

 mosomes. In the case of the meiotic divisions the whole process of 

 the transformation of the spireme Segments into the heterotype 

 chromosomes can be followed so continuously that there can be 

 but little doubt regarding the relation of one structure to the other. 

 Each spireme segment consists of two Univalent chromosomes ar- 

 ranged end to end, and each such pair develops, by concentration, 

 into one of the bivalent chromosomes of the heterotype division. 

 The number of chromosomes is about 115. 



Agnes Arber (Cambridge). 



Blake, S. F., Forms of Ophioglossum vulgatum in eastern 

 North America. (Rhodora. XV. p. 86—88. hg. 1. May 19, 1913.) 



In discussing the breadth of Variation in Ophioglossum vulgatum 

 the foUowing two extreme forms are recognized: f. pseudopodum 

 Blake and f. lanceolatum (Clute) Blake. The former, here described 

 as new, is figured. Maxon. 



Christensen, C, Polypodium speluncae L. A question ofno- 

 menclature. (Amer. Fern Journ. III. p. 1 — 4. Januar5^ 1913.) 



The name Polypodium speluncae was given by Linnaeus in 

 1753 to plants from India and Bermuda which were supposed to 



