DISEASES OF PLANTS. 03 



of the high concentration of these salts the stomata of the leaves close and the gas 

 exchange stops. In consequence of the deficiency of oxygen and carbohydrates no 

 new formation of chlorophyll takes place, while the chlorophyll previously formed 

 is destroyed by the light. 



A process thus takes place which is analogous to the turning yellow of the leaves 

 in the fall. If the absorption of the salts by the plant takes place in the normal way 

 no chlorosis is observed, because this absorption proceeds slowly, the plant being 

 provided with appliances which enable it to prevent an excessive concentration of 

 the salts in the leaves. When, on the contrary, the salts directly enter into the 

 plant through the exposed vessels of the roots these appliances prove insufficient and 

 do not function normally. 



Experiments by the author showed that solutions moving in the direction of the 

 least resistance first reach that part of the crown which corresponds to the respective 

 root branch. Herein is the explanation of the fact that usually chlorosis appears not 

 on the entire plant, but on certain or its parts corresponding to the injured branches 

 of the roots. The circumstance of the rapid absorption of solutions through exposed 

 vessels of the roots suggests to the author the proposition to utilize this phenomenon 

 for artificial nutrition and watering of fruit trees as well as for combating the enemies 

 of the latter. 



Whenever plant parasites or insects are the causes of injuries it is rational, in the 

 opinion of the author, to have recourse to the use of carbon disulphid, as is commonly 

 used for phylloxera. — p. fireman. 



Hetercecious rust fungi, II. Klkbahn (Die Wirtswechselnden Rostpilze. Berlin: 

 Borntrseger Bros., 1904, pp. XXXVII+474; rev. in Nature [London'], 69 (1904), No. 

 1800, pp. 601, 602). — The author treats of the general aspect and discusses the subject 

 of hetereeeism in rust fungi, after which special descriptions are given of the various 

 species in which this phenomenon has been recorded, the biology of each being 

 treated in detail. The various headings of the chapters indicate the scope of the 

 work. 



After defining heteroecism and giving a history of the subject, a summary is given 

 of the types of rust fungi involved. The means of distribution, germination, and 

 infection of the various kinds of spores are described and various controverted points 

 in the life history of the fungi are discussed. The author rejects Ericksson's myco- 

 plasma theory (E. S. R., 10, p. 316) as accounting for the wintering and subsequent 

 infection of the various host plants. 



The specialization of different rusts to certain host plants is described and atten- 

 tion called to some of the curious methods of infection between the related species. 

 A second part of the work is devoted to species of rusts and their biology. Extended 

 bibliographies are given and the work is completely indexed by species of fungi and 

 by the host plants. 



The grain smuts, L. A. Merrill and B. F. Eliason ( Utah Sta. Bul.84,}>p- 35-44). — 

 Compiled notes regarding grain smuts, the information being largely drawn from the 

 publications of this Department and the various experiment stations, and the results 

 of the authors' observations and the occurrence and distribution of smuts through- 

 out the State are given. The efficiency of various fungicides for the treatment of 

 seed is compared and directions given for their use. Based upon the efficiency, ease 

 with which the treatment may be followed, cost of treatment, etc., the use of formalin 

 is recommended. 



Treatment of seed grain for the prevention of smut ( Wisconsin Sta. Rpt. 1903, 

 pp. ?84-?92, jigs. 2). — This consists of abstracts of previous publicatons by R. A- 

 Moore, entitled Treating Seed Oats for the Prevention of Smut ( E. S. R., 13, pp.36, 

 962; 14, p. 957), Oat Smut Investigations for 1902 (E. S. R., 14, p. 958), Oat Smut in 

 Wisconsin (E. S. R., 13, p. 962), and Prevention of Oat Smut and Potato Scab 

 (E. S. R., 14, p. 978). 



