554 EXPERIMENT STATION RECORD. 



Studies on gummosis, J. Gruss and P. Soeaxjee (Notizbl. K. Bot. Gart. u. 

 Mus. Berlin, 5 {1910), No. ^7, pp. 188-197). — In a review and discussion of 

 gummosis of fruit trees, especially of the Amygdalacese, the authors claim that 

 this trouble results from a normal metabolic assimilation process in consequence 

 of wounds, nutrition disturbances, bacteria, etc., which cause irregularities in 

 the assimilation and nutrition processes. 



The diseases of the banana in Central America and Surinam, O. Labroy 

 {Jour. Agr. Trap., 10 {1910), No. 113, pp. 328-332) .—The author discusses the 

 so-called Panama disease of the banana which is threatening the total destruc- 

 tion in a few years of the entire banana plantations of Central America. The 

 opinions of various investigators as to the cause of this disease are given, fol- 

 lowed by a description of the symptoms of the disease and suggestions as to 

 its control. The planting of a variety of Congo banana which is highly resistant 

 to the disease is now in progress in Surinam. 



It is also claimed that a species of bee injures the epidermis of the young 

 bananas at flowering time, causing the fruit to become worthless for selling 

 purposes. 



Studies on the biology of Gymnosporang'iuni juniperinum, E. Fischeb 

 {Ztsclir. Bot., 2 {1910), No. 12, pp. 753-7'6-J ) .— The results are given of success- 

 ful cultures of a Gymnosporangium from Junipents commums on Sorhiis ter- 

 minalis and S. latifoUa, for which the name of O. termiiiali-jumperinum n. sp. 

 is proposed. 



G. juniperinum from J. communis infected S. aucuparia, 8. americana, and 

 S. hybrida. As cultures of G. amclanchieris on Aronia nigra, the usual host for 

 G. davisii, were unsuccessful, the author claims that the two rusts are not 

 identical. 



The fungus root tubercles of Ceanothus americanus, Elseagnus argentea, 

 and Myrica cerifera, E. G. Arzberger {Mo. Bot. Gard. Ann. Rpt., 21 {1910), 

 pp. 60-102, pis. 9). — After a brief historical review and summnry of the work 

 done by previous investigators on this subject, the author reports a study of 

 the external characters, internal structures, and the relationship of the fungus 

 to the host, of the tubercles on the roots of Ceanothus, Elseagnus, and Myrica. 



For the tubercles on Ceanothus it was found that the infection of the roots 

 was common and occurred through a root hair or an epidermal cell. Three dis- 

 tract stages in the life cycle of the fungus were noted, viz, (1) the mycelial 

 stage in the host cell, (2) the sporangia stage which initiates the conditions for 

 the digestive cell, and (3) the last stage where all but the walls of the mycelium 

 are absorbed. The nucleus of the invaded host cell at first increases in volume 

 and in the size of the nucleoli and the amount of chromatin present, but later, 

 following the vesicular stage, the cytoplasm and nucleus of the host cell are 

 absorbed. The cell contents of the fungus then disappear and both the host 

 cell and the fungus die. In the earlier stages of the tubercles symbiosis is 

 quite apparent, while later the fungus is able to dissolve the cell walls of the 

 host. 



In Elseagnus the fungus mycelium is much narrower than that of Ceanothus, 

 branches profusely and forms vesicles, the contents of which break up into 

 several segments. The fungus is not entirely absorbed by the digestive cell, 

 nor are the cell walls of the host broken down by the fungus. Both the host 

 cells and the fungus finally die. 



The tubercles and fungus of Myrica differ in many resiiects from those of 

 Ceanothus and Elseagnus. No hypertrophy or symbiotic relationship exists as 

 in the other two, and the fungus must be regarded as a parasite. 



