279 



Mr. Albert Miiller mentions its occurrence in great numbers in August, 

 on the flint gravel, covering the approaches to Elmer's End Station, 

 near London.* 



CRANBERRY LEAF-GALLS. 



By Dr. Fr. Thomas, Ohrdruff, Germany. 



The cranberry-galls mentioned in the periodical bulletin (Insect 

 Life, Yol. I, 1888, p. 112), looking like mite-galls of extremely small 

 size, are /lof made by Phytoptus or any other animal parasite, but by a 

 little unicellular fungus of the genus Synchytrium. The mite-galls of 

 a similar form we find on other plants are purse-like and furnished with 

 an opening, serving as a passage-way for the mites from the opposite 

 surface of the leaf. Microscopical investigation shows the cranberry- 

 galls as not purse-like, but chalice-shaped. On the bottom of the crim- 

 son chalice (at the base of the excavation) one cell is much increased 

 in size, the " host cell" of the parasite. It contains only one subglob- 

 ular fungus-cell, 0.086-0.171""^ in diameter, which has a brownish, 

 smooth wall ; its contents are colored by chrome-yellow oil. This "• rest- 

 ing spore" of the fungus resembles that of Synchytrium aureiim Schro- 

 ter, known in Europe as growing ujion a great many plants, in the 

 United States on Lysimachia quadrifolia L. (cf. Farlow, Botanical Ga- 

 zette, X, p. 242), but till now unknown or at least undescribed as a gall- 

 maker of V'accinium. I do not believe that the Synchytrium vaccinii, 

 which T^roduces the cranberry-galls, belongs to the former species, no 

 chalice-shaped gall caused by Synchytrium aureum having been found 

 yet. 



In autumn the cranberry-galls become black and brittle and break 

 off. The resting spores of the fungus fall down to the ground or are set 

 free hy the rotting away of the leaves. Next spring the spore germi- 

 nates, produces (in a manner still to be stated for this species) zoospores, 

 swimming in water for some time and attaching themselves to epidermal 

 cells of a young cranberry-leaf to re-commence the production of galls. 

 Thus the parasite spreads by water, an infection that can not be lim- 

 ited in a locality in which water sometimes overtlows all the ground or 

 runs from one part to the other. A long flooding of the bog can not 

 but result in the further distribution of the disease. The single remedy, 

 I mean, would be to draw out all plants covered with galls in summer 

 or autumn before the resting spores escape. 



^ Eutomologist's Monthly Magazine, 18fi7-'68, p. 71. 



Note. — Early iu December, 1^88, Hou. L. B. Custer, of Logansport, Ind., applied 

 to me for a remedy for a species of mite which had taken possession of a dwelling 

 in his city, coming in through the crevices about the windows, as observed by the 

 lady of the house, they having been also observed in the same house the preceding 

 spring. — F. M. W. 



