Observations on the "Slime-fluxes" of trees. 171 



B. Oospora [Oidium) lactis var. I. 



This accompanies the Fusarium fairly constantly. 



Cultural characters. Produces a beautiful colony on beer- 

 wort gelatine at room temperature, consisting of a central zone 

 of irregular wavy Hues from which there extend outwards 

 towards the circumference undulating radial lines. Surface 

 powder}' (owing to production of aerial conidia). On rich, moist 

 media such as sterile carrots, moist beer- wort agar, etc., a slim\' 

 yeast-like growth. In neutral beer-wort no fermentation or 

 surface film after six weeks. 



Morphological characters. Branching usually as in Oospora 

 {Oidium) lactis. Primary hyphae 8-5-13 /z, av. 11 /^i, secondary 

 or branch hyphae z-^-^-jfi in diameter. Hyphal cells rect- 

 angular with somewhat rounded ends, up to 100 fx long. Conidia 

 on primary and secondary hyphae in erect chains, conidiophore 

 short or absent. Ends of h^^phae breaking up into oidia, 

 3'5-ii/Li X 2'5-5-5/Lt (av. 7 x ^-^fj,), rarely globular. Chlamydo- 

 spores produced abundantly on short stalks from the h^'phal 

 cells after seven days on beer- wort agar at 26' C. Diameter 

 when ripe about ii/x. Spore wall double. 



This form of Oospora {Oidium) lactis appears to be distinct 

 from any of those described bv En\in Schnell(i3). 



C. Other organisms. 



As already stated the Fusarium and Oospora occur with 

 remarkable constancy. Other fungi are comparatively few in 

 number. The writer has ionnd Trichothecium roseum (Pers.) Link 

 and the blue Fusarium strain found in the t\*pical brown fluxes. 

 Protozoa, insect lar\*ae and algae are not so common as in these. 



3. Brown Variety. 

 (a) General. 



This t^'pe of flux has been found ver\' commonly in and 

 around Cambridge on elms, especially on Ulmus campestris and 

 Ulmus vegeta, and on horse-chestnuts. It frequently occurs on 

 Ulmus montana in Aberdeenshire. 



So far as the writers obser\'ations go, it is alwa3"s associated 

 with some wound, such as abrasions of bark due to animals, 

 frost cracks, woimds made by nails, branch snags, etc. It 

 appears to have its origin in the heart wood, and consists of a 

 thick brown or yellowish brown fluid, somewhat of the con- 

 sistency of porridge. 



In the case of branch scars the flux begins as a somewhat 

 copious exudation of a clear waterv fluid from the heart wood. 

 This fluid is soon invaded by bacteria, fimgi and yeasts, such 

 as Isaria, Torula, Alternaria, pink veasts, etc. After about a 



