576 SUMMARY OF CUKRENT RESEARCHES RELATING TO 



described as new by Wright, is identical with W. Chamissoi Brack, 

 (1854) from California, and also with W. spinulosa Mart, and G-aleotti 

 (1842) from Mexico, both of which in time past have been wrongly 

 referred to W. radicans. And he makes this unnecessary creation of a 

 new name the text for a severe homily directed against European pterido- 

 logists, especially those of the Hookerian school. He commends the 

 following suggestions to the attention of European fern students : 

 " 1. Make a study of geographic distribution in its relation to specific 

 limitations. 2. Consider type locality as a fundamental part of a plant 

 description ; it is the lack of this element that makes Christensen's 

 Index just short of the ideal. 3. Beware of any species with a wide 

 range as recorded in Synopsis Filicum or that has any extended synonymy 

 either there or in Species Filicum ; there are few species of world-wide 

 distribution, and there will be sure to be something wrong with wholesale 

 slaughter ; these are danger marks not to be disregarded. 4. Synonyms 

 and homonyms are still important factors in taxonomy." 



VuiLLEMiN, p. — Sur les variations de rEquisetum palustre L. (On the variations 

 of EquiseUivi palustre L.) 



[From a study of the numerous transitions exhibited by examples of this 



species, gathered at the same spot on the same day, the author is led to 



conclude that there is not any absolute difference between Equiseta with 



uniform shoots and Equiseta with dimorphous fertile and sterile shoots.] 



Bull. Soc. Bot. France, liii. (1906) pp. 37-45 (1 fig.). 



Bryophyta. 



(By A. Gepp.) 



Reproduction of Mosses and Ferns.* — J. Burton gives a plain and 

 generalised account of the reproduction of mosses and ferns in the 

 simplest language consistent with accuracy. He defines sexual and non- 

 sexual reproduction, and describes the alternation of generations in detail 

 as occurring in the life-history of the mosses on the one hand and in 

 that of the ferns on the other, indicating the main points of contrast 

 and coiTespondence. In conclusion, he shows that in each case the 

 result of the fertilisation of the oosphere is a more highly developed 

 structm'e than that which results from the spore. For even in the 

 mosses the mere cellular tissue of the oophyte has a far lower organisa- 

 tion than the sporophyte with its inner columella surrounded by a ring 

 of spore-producing tissue, outside which is the assimilatory tissue with 

 its air-spaces, the sub-epidermal tissue, and the strongly developed 

 epidermis with its stomata. 



Problems of Moss Distribution. f — A. Geheeb discusses the distribu- 

 tion of Tetraplodon mnioides in Germany. It is an arctic and alpine 

 moss, seldom occurring in the north German plain. Yet it has recently 

 been recorded as occurring abundantly and fruiting freely at Rheine in 

 Westphalia, though unknown in precisely similar surroundings in the 

 rest of the province. In attempting to explain its occurrence, Geheeb 

 quotes a theory that the spores have been carried by the wind from the 



* Journ. Quekett Micr. Club, x. (1907) pp. 1-3. 

 t Rev. Bryolog., xxxiv. (1907) pp. 76-7. 



