3 46 SUMMARY OF CURRENT RESEARCHES RELATING TO 



small, the effect passes off withont leaving any trace. It was found that 

 some animals are much more susceptible than others to the poison. 



Deformations Caused by G-ymnosporangium.* — L. Geneau de 

 Lamarliere has examined the differences in the effects produced on their 

 alternate hosts by Gymnosporangium clavar'mforme and G. juniper inum. 

 He finds that the results on the tissues of the host-plant are very 

 similar in both species. There is deformation and hypertrophy of the 

 tissues of the parenchyma resulting in the swelling of the organ attacked, 

 and due to the development of the mycelium of the parasite. In the 

 action of the Roestelia or JEcidium form, the part of the plant infected 

 is killed by the fungus ; in the teleutospore form, a kind of symbiosis is 

 established between the mycelium of the Gymnosporangium and the 

 tissue of the Juniper ; the effect is not fatal as in the case of the 

 Roestelia. In the latter the cambium is attacked — the conducting 

 tissue — which leads to the death of the branch or leaves attacked. 



Uredineae. — W. A. Kellermanf gives an account of his experiments 

 with the rust of maize, Puccinia Sorghi, the JEcidium of which grows on 

 Oxalis. While the rust itself is common, the JEcidium is rare, and the 

 fungus is propagated from year to year by surviving uredospores. 



J. C. Arthur | describes in detail the cultures of Uredineas made 

 during 1905. In many instances previous results were verified. 

 Negative results on new material are also chronicled. Successful inocu- 

 lations were obtained in nine species not previously chronicled. A 

 hetercecious form was proved : the^Jcidium on Steironema, the Puccinia 

 on Spartina. Here again the JEcidium is rare, and propagation un- 

 doubtedly due to the hardiness of the uredospores which enables them 

 to persist during the winter and infect the plants in spring. 



A large canker growth on a species of Bignonia, from Brazil, has 

 been found by P. Magnus § to be caused by a new fungus, Uropyxis 

 Rickiana. The mycelium of the Uredine burrows in the cortical 

 parenchyma, and forms a spore layer, which bursts the epidermis of the 

 host. The tissue underlying the spore layer grows vigorously, and 

 forms a layer of cork which is burst in turn as a new spore layer is 

 formed beneath. The presence of the fungus induces a rich formation 

 of vascular tissue as well as of cork, and a very large canker is formed. 

 The author found only the teleutospores of the fungus. These are two- 

 celled, and each cell possesses two germinating pores. 



Tracya Hydrocharidis Lagerh.|| — This member of the Tilletiae was 

 found in the leaves of Hydrocharis Morsus-ranoz near Stockholm by 

 E. Renkauf- Weimar, who writes a description of it, and of the germina- 

 tion of the spores and the formation and fusion of the sporidia. These 

 develop a germinating tube which penetrates the young leaves and 

 forms abundant mycelium in the air-spaces of the spongy parenchyma ; 

 gradually a ball of hyphas and spores is produced. The author found 

 the fungus only on the leaves. They become brown and the spore- 



* Ann. Sci. Nat., ser. 9, ii. (1905) pp. 313-50 (4 pis.). 

 t Journ. Mycol., xii. (1906) pp. 9-11. % Tom. cit., pp. 11-27. 



§ Hedwigia, xlv. (1906) pp. 173-7 (1 pi.). 

 || Op. cit., (1905) pp. 36-9 (1 pi.). 



