1912} CURRENT LITERATURE 439 



does not occur in definite bundles, and the rays of Aptiana are multiseriate. 

 The question of genetic connections must await further information, but the 

 author well remarks that the chief importance of these three genera "is that 

 they are so old, and that they prove the existence of undoubted higher woody 

 angiosperms in Northern Europe at this time." — J. M. C. 



The biology of Uredinales. An excellent summary of our knowledge 

 of Uredinales is given by Maire. 28 Since the article is itself of the nature of a 

 review, it needs to be mentioned here merely with reference to its scope, and 

 to indicate new matter and views introduced by the author. The subject 

 is treated under two heads: (i) the individual evolution and the sexuality of 

 the Uredinales, and (2) the relation of the Uredinales to their hosts and to their 

 environment. 



The first part is chiefly an account of recent progress in the cytology of 

 the rusts, with a brief exposition of the theories regarding their origin. The 

 author himself believes the Uredinales and the higher Basidiomycetes to have 

 had a common origin with the Ascomycetes. This view is based mainly on the 

 presence of apparently functionless spermatia in the rusts and in some of the 

 Ascornycetes, and on the existence of minute conidia possibly representing 

 ancestral male cells among the Basidiomycetes. 



In connection with the discussion of those rusts which have shortened 

 life histories, the author introduces an amplification of Schroeter's classi- 

 fication of these forms. By taking into consideration all the spore forms, 

 including the spermatia, he obtains the following biological groups: O-I-II- 

 III, ew-Uredinales ; I-II-III, ^to-Uredinales; O-II-III, bracky-XJredinales; 

 O-III, /iy£0-Uredinales; O-I-III, 0/w-Uredinales ; I-III, catopsi-XJiedinales; 

 II-III, hemi-Vredinales; II, />y/-0-Uredinales. Heteroecism and autoecism 

 are expressed by the prefixes hetero- and auto- in the manner suggested by 



DUGGAR. 



The second part takes up such more general phases of the work on biology 

 of rusts as the types of development of the Uredinales, the role of the different 

 spore forms, dissemination and infection, and the more theoretical questions 

 relating to the host-relationships and the origin of species and of heteroecism 

 within the group, and finally the various types of morphogenic changes induced 

 by rusts in their hosts.— H. Hasselbring. 



The mistletoes.— At the April meeting of the National Academy of 

 Sciences, Dr. Trelease presented a revision of Phoradendron. An abstract 

 of his paper is as follows: There are distinguished 83 forms of this exclusively 

 American genus of mistletoes on the mainland north of the Isthmus, of which 

 72 are regarded as species and the remaining 11 as varieties. About half of 

 them are Mexican, one-fourth Central American, and one-fourth belong to the 



28 Maire, Ren£, La biologie des Uredinales. Progressus Rei Bot. 4:110-162. 



1911. 



