88 SUMMARY OF CURHENT RESEARCHES RELATING TO 



and found by him to be due to a fungus, Monilochsetesjnfnscans g. et 

 sp 



n. He gave no technical account of the fungus. The disease has 



again been examined by L. Ti. Barter, who now describes both the 

 disease and the fungus. The latter, a member of the Dematiacefe, is 

 superficial on the potato and causes a brown discoloration, but does not 

 penetrate the epidermis. 



Disease of Trees."'— "W. H. Long has investigated the heart-rot of 

 oaks caused by Stereum subpileatimi. The fungus enters the wood of 

 the host only through wounds that expose the heart-woods, through 

 fire-scars or through branch stubs. The heart-wood is delignified by the 

 action of the fungus. The sporophores were found only on dead trees 

 or on dead areas of living trees. The rot is very widely distributed in 

 America. 



A root-rot of apple-trees in North Carolina has been determined by 

 F. Wolf and R. 0. Cromwell f to be due to Xylaria sp. The disease 

 has been notified from various parts of the State and elsewhere. The 

 roots are covered with black fungus incrustations, from the margins of 

 which radiate minute black rhizomorphs. The cortex becomes corroded, 

 and the disintegration of the wood follows, although slowly. 



P. A. van der Byl | has given an account of Polyporns lucidus which 

 has caused the death of many acacia trees around Pretoria. He gives a 

 systematic resume of allied or synonymous species, and a description of 

 the fungus itself and of its development within the tissues. The hyphfe 

 do not pierce the M'alls of the wood vessels, they gain entrance by the 

 pits. The fungus is a wound parasite, and the trees attacked are mostly 

 in a previously enfeebled condition. 



Endotrophic Mycorhiza of Ericace3e.§— Jean Dufrenoy has made a 

 study of Mycorhiza in Arbutus Unedo. He finds that the roots are 

 clothed with a dense mantle of hyphte, some branches of which penetrate 

 the tissues of the root, and haustoria are formed in the living cells of 

 the host. Rootlets which have been inoculated early cease to grow 

 apically and form tubercles. The base of the shoot also develops into 

 a very large tubercle from which many lateral stems spring. The 

 fungus penetrates into every part of the tree, even into the assimilating 

 and reproductive tissues. The writer discusses the relations between 

 the host-plant and the invading parasite. 



Lichens. 



(By A. LoBRAiN Smith, F.L.S.) 



Attachment Organs of Corticolous Ramalin8B.||— LiUan Porter 

 gives a historical account of work done on the anatomy of the Ramalinae, 

 especially with regard to their organs of attachment. She then describes 



* Jouru. Agric. Research, v. (1915) pp. 421-8 (1 pL). 



t Journ. Agric. Research, ix. (1917) pp. 269-76 (3 pis. and 4 figs.). 



X South African Journ. Sci., xiii. (1917) pp. 506-15 (5 pis. and 6 figs.). 



§ New Phytologist, xvi. (1917) pp. 222-8 (4 figs.). 



II Proc. Roy, Irish Acad., xxxiv. (1917) pp. 17-32 (3 pis.). 



