ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 79 



Fungi. 

 (By A. LoRRAiN Smith, P.L.S.) 



New Phycomycete.* — H. A. Edison describes a new genus and 

 species, Rheosporangium aphanidermatus, which causes damping off of , 

 seedlings of sugar-beet and of radishes, to which he referred in a previous 

 paper as an nndescribed member of the SaprolegniacCc-e. The new 

 fungus resembles Fythium Debaryannm except in the asexual frniting- 

 stage. The mycelium is aerial or aquatic ; reproduction is by zoospores 

 under aquatic conditions and by oospores. From the hyphfe is cast off 

 a terminal swollen portion termed the prezoosporangium, which ruptures 

 and allows the escape of the contents ; this body becomes surrounded hj 

 a delicate wall, and by cleavage forms zoospores. 



Rhizophidium acuforme.t — This minute Phycomycete was found 

 by W. B. Grove on cells of Chlnmydomonas intermedia in a cart-rut. 

 He describes the growth and development of the parasite, the bursting 

 of the sporangia, and the reinfection of the algje by the zoospores. No 

 resting spores were seen. 



Entomophthora americana.i — Hugh Main reports this species, new 

 to Britain, from Epping Forest. It was collected in August, 1916, on 

 the trunk of a hornbeam, about three feet from the ground. It 

 consisted of a mass of white hyphte growing from the body of a large 

 fly which has been identified by K. G. Blair as Hyetodesia erratica. 

 J. Ramsbottom examined the fungus and found it identical with the 

 above species of Entomophthora. 



PeronosporaceaB.§ — I. E. Melhus comments on the reported perennial 

 condition of Pliytophthora infestans in the Irish potato, and he points 

 out that perennial species have been determined belonging to four genera,, 

 the mycelium passing the winter either in the aerial or the underground 

 organs of winter annuals, biennials, or perennials. 



In a further paper Melhus |1 describes his culture experiments with 

 PhyJophtliora infestans, and he claims to have proved that the mycelium 

 persists in the tube, and from it passes into the shoots. The planting of 

 diseased tubers may thus give rise to an epidemic. He found no 

 evidence that conidia in the soil gave rise to new infections. 



Discharge of Spores of Leptosphaeria acuta.! — W. J. Hodgetts 

 has followed the process of spore discharge by mounting ripe perithecia 

 in water and withdrawing the hymeniuni. The outer wall of the ascus 

 is burst by the spores still enclosed in the inner gelatinous wall, which 



* Journ. Agric. Research, iv. (1915) pp. 279-91 (4 pis.). 



+ New Phytologisf, xvi. (1917) pp. 177-80 (1 fi^.). 



X Essex Naturalist, xviii. (1917) pp. 107-8 (1 fig.). 



§ Journ. Agric. Research, v. (1916) pp. 59-69 (1 pi. and 1 fig.). 



li Journ. Agric. Research, v. (1916) pp. 71-102 (5 pis.). 



t New Phvtologist, xvi. (1917) pp. 139-46 (14 figs.). 



