616 8. Abstammungslehre. 



leur positiou aux deux points du spectre oü se fixent les sulfuraires. Ces 

 deux points sont situes respectivement vers ^,= 780 — 790 etvers jl == 820 — 840. 

 Les sulfuraires sont tres sensibles aux radiations et leur pigment est decolore 

 par les radiations rouges et infra-rouges qui produisent la fixation. 



Ce sont ces memes radiations qui permettent le developpement des 

 cultures de sulfuraires. C. L. Gatin (Paris). 



1707) Johnson, E. C, Timothy Rust in the United States. 



(U. S. Dept. of Agr. Bur. Plant Ind. Bulletin 224. p. 1—20. 1911.) 



Pearl (Orono). 



1708) Freeman, E. M. and E. C. Johnson, The Rusts of Grains in 

 the United States. 



(U. S. Dept. Agr. Bur. Plant Ind. Bulletin 216. p. 1-87. 1911.) 

 This is a very thorough study of the live history, taxonomy, and physio- 

 logy of grain rusts (Puccinia spp.). Special attention was given to the diffe- 

 rent „biological forms" or strains of these rusts on different host plants. 

 In this line many data of interest to the Student of evolution are presented. 

 The influence of environmental factors (particularly temperature) on the vita- 

 lity of uredo generations was especially studied. A brief summary of the 

 results is not possible. Pearl (Orono). 



1709) Olive, E. W., Origin of heteroecism in the Rusts. 



(Phytopathology 1. p. 139—149. 1911.) 



An attempt is made, to answer the question how the heteroecious rusts 

 were derived in an evolutionary way from a previous autoecious condition, 

 and which of the two hosts was the primary one. For instance, in the case 

 of Puccinia graminis, was wheat or the barberry the original host form? 

 Various views are discussed. 



Teleutospores are believed to be the only spore form of the ancestral 

 rusts. The author believes that the rusts having more complex life histories 

 were derived phylogenetically from „the simpler lepto- and micro-forms by 

 progressive development of the sporophyte". It is concluded that the present 

 gametophytic host, or that in which the sexual fusions occur, should be „re- 

 garded as the original host of the hypothetical autoecious ancestor of the 

 present day heteroecious rust". This conclusion is based on several conside- 

 rations: 1. Since the uninucleate gametophyte is the more primitive condition, 

 the primary host of the autoecious ancestor was probably the present host of 

 this gametophyte, the present sporophyte host being secondary. 2. The Stimu- 

 lus resulting from the sexual fusions is supposed to endow the diploid aecidio- 

 spores produced soon afterwards, with greater vigor, so that they are most 

 capable of infecting foreign protoplasm. The original jump to secondary hosts 

 was therefore probably performed by the aecidiospores and not by the uni- 

 nucleate basidiospores. 3. The prevalence of heteroecious forms having sporo- 

 phytes on several different hosts, argues for the theory that this habit resulted 

 from the invigorating influence of the sexual fusions. Further, the fewness 

 and close relationship of the gametophyte hosts (frequently Gramineae and 

 Cyperaceae), as well as the multiplicity and remote relationship of the sporo- 

 phytic hosts, indicates that the present gametophytic hosts were the primary 

 hosts of an original autoecious ancestor. Gates (London). 



1710) Malinowski, E.,Przyczynek do biologii i ekologii porostöw epi- 

 litycznych. — Sur la biologie et l'ecologie des lichens epilithiques. 



(Anz. der Akad. d. Wissensch. in Krakau. Math.-nat. Kl. 5B. p. 349—391. 



6 Abb. u. 9 Photogr. 1911.) 



Bruno Kisch (Prag). 



