MYC0L0GICAL NOTES 43 



which extended in a north-easterly direction to a distance of about 

 three feet, and in other directions less. Near the second bundle 

 no aecidium could be observed ; the nettles round A were thickly 

 covered with it. 



On this same day (April 27th), a third and similar bundle of 

 last year's Carex was conveyed from A to C and laid amidst a bed 

 of nettles, which at this time were well above ground. The pools 

 were examined again, after a rainy period, on May 27th, when at 

 A and round the first bundle at B, a second crop of aecidia 

 (arising from a second outburst of basidiospores), was seen to be 

 just making its appearance ; on visiting the second bundle at B, a 

 few patches of spermogones and aecidia were visible on the nettles 

 nearest in an easterly direction, about three yards away, but 

 nowhere else. On reaching C, at first sight it seemed as if the 

 experiment had failed; the tall nettle-stems around the bundle 

 showed no signs of aecidia, but on looking underneath it could be 

 seen that a few stems had the leaves affected quite close to the 

 bundle, to a height of about four or five inches only from the 

 ground. In this case the effect of air-currents was hindered both 

 by the trees and by the nettle-stems which grew around in dense 

 array. 



Since the prevailing winds are westerly, it was obvious that 

 they could not blow the basidio-, aecidio-, or uredo-spores from A 

 to B, and the easterly winds were rendered ineffectual by the belts 

 of trees. The westerly winds could have blown the basidiospores 

 from A to C, but did not do so effectually on account either of the 

 distance or of the surrounding trees. 



There is another pool, D, about three hundred yards to the 

 south-east of A, having abundance of both Carex and nettles, and 

 densely surrounded by trees. Here nothing has been done, and 

 the nettles this year, as in all previous years, were perfectly devoid 

 of infection. 



From these facts two inferences can be drawn : (1) That the 

 chief means of distribution of the spores of the Uredineae is the 

 wind, but the efficiency of this agent can be reduced to very 

 narrow limits by other factors, e. g., in the case of B perhaps not 

 one basidiospore in a billion reached a nettle-leaf and germinated 

 successfully ; and (2) That one can introduce P. Caricis into any 

 suitable locality, three things being given — Carex, the common 

 nettle, and a bundle of infested leaves of the former. C. pakidosa 

 is the best, but C. hirta, C. pendula, C. Psetidocyperus, and 

 C. riparia will also do. The month of January appears to be the 

 best time for the operation, which presents this advantage com- 

 pared with some others of like kind, that the two plants affected 

 by it are both common, and that no agriculturist or horticulturist 

 can object to their infection, since both of them are useless or 

 injurious. 



Phoma pigmentivora Mass. In the Kew Bulletin for 1911 

 (p. 325, with plate) is a very interesting account of this new 

 fungus, which lives upon the oil of white paint. I have since 

 found the fungus (which I had never seen before) at several 



