ZOOLOGY AND BOTANY, MICKOSCOPY, ETC. 219 



of a pit-closing membrane — a matter of dispute in all vascular Cryptogams. 

 Halft and Bancroft have proved the presence of the membrane, but did 

 not study the Ophioglossacea?. This omission the present author makes 

 good by figures and description. Only with the greatest difficulty could 

 the membrane be demonstrated clearly in Helminthostachys, but more 

 easily in Ophioglossum and Botrychium. The methods of staining are 

 explained ; and the torus or thickening of the membrane is discussed. 



A. G. 



Some Impressions of Pteris aquilina L. in the Tufa of the Villa 

 Torlonia at Frascati. — R. Meli {Atti Pontif, Accad, Romana del 

 Nuovi LinceL, 1919, 71, 49-64). A resume of papers previously pub- 

 lished upon this subject, with criticisms and additional information . The 

 living ferns were buried in position by a fall of volcanic dust and cinders, 

 thus diifering from other instances, as from the Valley of the Tiber and 

 of the Sacco, and from Onano in the Vulsini, where the impressions, 

 mingled with those of other plants, are mostly disposed horizontally in 

 the tufa. A. G. 



Norfolk Island Species of Pteris.— R. M. Laing {Trans. Proc. New 

 Zealand List., 191G, 48, 229-37, figs.). A revision based on good and 

 abundant material, and an attempt to identify with certainty Endlicher's 

 species, described in 1833. The results are as follows : — A. Veins 

 forked — (1) Pteridium esmdentum Cockayne {Pteris escidenta Forst. f.) ; 

 (2) Pteris tremida R. Br., P. Baueriana Dies.) ; (3) P. Kingiana Endl. ; 

 (4) P. biaurifa L. var. quadriaurita Retz. (? P. TrattinicJciana Endl). 

 B. Veins anastomosing— (5) P. comans Forst. f. (? P . ZaMhruckneriana 

 Endl); (6) P. Brunoniana Endl.; (7) Histiopteris {Pteris) incisa 

 (Thunb.) J. Sm. The author contends that P. Brunoniana is a good 

 species. The text-figures are clear and accurate. A. G. 



Bryophyta. 



Spermatogenesis in Blasia. — Lester W. Sharp {Bot. Gaz., 1920, 

 69, 258-68, 1 pL). An account of spermatogenesis observed in Blasia 

 pusilla collected near Chicago. 1. Centrosomes are present at ail stages 

 of the mitosis which differentiates the androcytes, and in the androcytes 

 they persist and function as the blepharoplasts. 2. In the transforma- 

 tion of the androcyte into the spermatozoid, the blepharoplast divides 

 repeatedly by simple fission, forming a number of distinct granules 

 which coalesce to form a short lumpy rod. This rod elongates and 

 becomes a more uniform thread bearing two cilia, while the nucleus also 

 elongates in intimate union with it to form the body of the spermatozoid. 

 The present instance is the first in which blepharoplast fragmentation 

 has been reported in a Bryophyte. 3. It is possible that the fission of 

 the Blasia blepharoplast, and therefore the more complex fragmentation 

 of the blepharoplasts of Eqtnseium, Marsdia, and the Cycads, may be 

 homologized with the normal division exhibited by ordinary centro- 

 somes. A. G. 



