102 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Empusa ox Entomophihora, but as the conidial fructification is unknown, 

 that point cannot be decided. The mycelium of the fungus consists of 

 spirally twisted, mostly non-septate hyphae. The resting spores, which 

 are the only fructification noted, arise at the tips of the hypha3, and 

 swell to a much thicker size ; they are yellowish in colour. It inhabits 

 flies under leaves. 



Lakon describes and criticizes the different species of this as well 

 as of neighbouring genera, He also considers the question of utilizing 

 the fungus as a means of infecting and so reducing the number of flies, 

 but he does not think tliat on the whole it is of much practical value as 

 an exterminating disease. 



Systematic Position of Endogone.* — K. Kavina discusses the 

 varying opinions as to the significance of the ampulla which are a 

 feature of this fungus. Buchholz held that they arose through copula- 

 tion of the heterogamous ends of hyph», but Kavina could find no 

 trace of such a copulation. He considers them rather to be sporangia 

 somewhat similar to those of the Mucoraceas. He therefore places 

 Endofjone among the Phycomycetes as an independent family Endo- 

 gonaceae. 



Biology of the Oak Mildew.f — Roth has found that this mildew 

 grows more freely in full sunlight than in the shade, and he thinks this 

 is due to the effect of light on the fungus, and not to the formation by 

 the host-plant of more luxurious shoots or of leaves turgid with sap. 

 He thinks that to some extent the mildew might be checked by shade, 

 though that would delay the growth of the young oaks. Advice is 

 given as to sulphuring attacked trees. 



Infection and Immunity Studies on the Apple and Pear Scale 

 Fungi.J — S. P. Wiltshire has studied infection by the two fungi 

 Venturia inseqmtUs and V. pirina in the conidial stage. The conidia of 

 the former produces a terminal germ-tube, in the other the tube is 

 lateral ; in both a " collar " or flange arises at the apex of the germinating 

 hypha, apparently as an excretion, and it serves to attach it to the cuticle 

 of the host. From beneath the flange a hypha is produced which 

 pierces the cuticle of old leaves, and even of resistant varieties, though 

 only in young leaves of susceptible plants is there any further develop- 

 ment ; in these a mycelium is formed between the cuticle and the 

 epidermal cells. Immunity, the author concludes, does not depend on 

 protection by the cuticle, nor does chemotropism play any part, as the 

 hyphag run horizontally ; he thinks that, on the contrary, the cell sap 

 of the host mav even be antagonistic to the fungus. 



*&^ 



* Vestnik V. sjez. ces. prir. (1915) p. 347. (Bohemiau.) See also Bot. Centralbl., 

 cxxix. (1915) p. 381. 



+ Naturw. Forst. Landw., xiii. (1915) pp. 260-70. See also Bot. Centralb., cxxix. 

 (1915) p. 443. 



X Ann. Appl. Biol., i. (1915) pp. 335-49. See also Bot. Centralbl., cxxix. (1915) 

 pp. 570-1. 



