126 Eumycetes. — Pflanzenkrankheiten. 



water. A very regulär stout mycelium is produced, and in about 

 twelve hours from the time of sowing microconidiophores are formed. 

 A little later, in about 24 hours, macroconidiophores are produced 

 in addition, after which the colour of the culture gradually changes 

 from white to black. The microconidiophore consists of a sterile basal 

 portion, 1 — 3 septate, surmounted by a long tapering tube. The 

 spores are formed one by one in the tube, a cell wall being developed 

 round the protoplasm in the apex, and each spore is extruded by 

 the expansion of the protoplasm behind it. Each conidiophore may 

 form as many as 80 spores, which hang together in chains in the 

 nutrient fluid. 



The macroconidiophores are not unlike the microconidiophores 

 in structure. When mature the apex dissolves and some of the pro- 

 toplasm is extruded , which forms a cell wall. This process is repeated 

 until 1 — 20 macrospores have been formed. 



Under certain conditions conidiophores are produced in curious 

 groups, forming the "Stysanus-like" fructification. 



Oxygen is essential to the growth of the fungus, and growth is 

 more luxuriant in darkness than in light. Spores may retain their 

 germinative capacity for over a year. 



The effects of various fungicides on the spores were tested. 

 With tannic acid, carbolic acid, and copper sulphate germination is 

 inhibited by a much lower concentration of the toxic substance than 

 is required to kill the spores. The fungicidal value of Copper Sul- 

 phate for this fungus is proved to be remarkably low. 



A bibliography is appended. W. E. Brenchley. 



Bancpoft, K., The Die-back disease of Para Rubber, and 

 a note on the Leaf- diseases ofPara Rubber. (Bull. N°. 14. 

 Dept. Agric. Federated Malay States, p. 1—23. ill. 1911.) 



The disease is attributed to a Diplodia, concluded to be a stage 

 of the fungus Thyridaria tarda. It attacks the stem, obtaining access 

 through wounds of various kinds. The terminal part of the shoot 

 dies, and the disease spreads downwards, eventually killing the 

 tree to its very base. Diagrams indicate the course of the disease, 

 and certain irregularities in its progress are described. Trees are 

 usually attacked individually, not in groups. The fungus is propa- 

 gated by spores, dispersed by wind and insects. Attacks of "die-back" 

 frequently follow attacks of the "pink" disease to which the Rubber 

 is subject. For treatment all diseased portions should be cut out, 

 and all wounds tarred as a preventive. 



A note is appended on the leaf diseases of Para Rubber caused 

 by Pestalossia Guepini and P. Palmarum, Phyllosticta Heveae, Hel- 

 minthosporium Heveae, Gloeosporium elasticae and G. brunneum, 

 Colletotrichum Heveae and Ophiobolus Heveae. W. E. Brenchley. 



Hill, A. W., Conifers damaged by Squirrels. (New Phyto- 

 logist. X. p. 340—342. 1 plate. 1911.) 



Thuya plicata and Cupressus Lawsoniana with bark removed by 

 Sciurus, but left in places at the bases of branches. These remained 

 alive, callus was formed, and water was evidently conducted through 

 wood unprotected by cortex and bark. Comparison with parasitism 

 of Viscum is also made. W. G. Smith. 



