316 NOTES AND MEMORANDA. 



small spores, each of which becomes a myxamceba. These penetrate 

 into the tissue of the root, and develop into a new plasmodium, though 

 whether by the coalescence of a number of myxamoebae is still un- 

 certain. In addition to the Plasmodiophora, Woronin found in the 

 diseased roots a new Chytriclium (C. Brassicce), propagated by zoo- 

 spores. The zoosporangium has a globular base, and is elongated 

 above into a hmg neck, which oj)ens to allow the escape of the 

 zoospores, usually outside the tissue of the host. Eesting-spores 

 were also observed, probably formed, as in other Chytridiaceaj, by the 

 coalescence of two zoospores, though Woronin has not at present been 

 able actually to detect this process. Similar malformations found on 

 the roots of many other plants, especially Leguminosaa, are probably 

 due to the attacks of fungi of the same nature. 



Fungus Disease in Lettuces (Peronospora gangliiformis). — Eefer- 

 ring to this subject (see page 167), MM. Bergeret and Moreau have 

 found * that water very slightly acidulated with nitric acid constitutes 

 a good remedy for the disease. This solution has the double advan- 

 tage of being a manure for the soil, and a poison to the fungus; or at 

 least a means of arresting its development. 



Fungi of Stalactites. — Fungi play an important and hitherto 

 unnoticed part in stalactitic distortion. In an account f of an explo- 

 ration of the Luray Cavern, Virginia, U.S., Mr. H. C. Hovey says 

 that his attention was called to numerous fine elastic bristles growing 

 on stalactites and other kinds of dripstone in all parts of the cavern. 

 Each carried a little ball at its extremity usually enveloped by a 

 globule of water, and he further observed that the conditions often 

 favoured a thin deposit of the carbonate of lime on these bristles, so 

 that their shape remained after the substance had decayed. Many of 

 these black setae and white filaments were examined by the Microscope, 

 and the gradations were traced from the finest hairs up to great knots 

 and tangled outgrowths. 



This fungus is a new species of Mucor, to which he gives the name 

 of M. stalactitis. Sporangia globose, membranaceous, dehiscing by a 

 fissure, terminating threads ; sporidia sub-globose and separating ; 

 flocci tubular, indistinctly partitional, sometimes branching at the 

 base, but never at the apex. Specific marks : Sub-solitary threads ; 

 sporangia simple ; height -^^ to i inch ; colour dark olive-green. 



Conidial Fructification of Fumago. — W. Zopf has written a trea- 

 tise on this subject,! in which he showed that the conidial fructification 

 of this fungus is obtained only when it is cultivated on a substratum 

 of a highly nourishing character. When the supply of nutriment is 

 deficient, thi-ee forms may be obtained ; the yeast-like budding-plants, 

 in a fluid ; the mycoderma and chalara-like forms, on the surface of a 

 fluid ; and mycelial plants bearing micro-gonidia (aerial form), on a 

 solid dry substratum. He had never, notwithstanding long trials, 

 been able to obtain the large-spored pycnidia or the asci. 



* 'Comptes Eendus,' Ixxxviii. (1879) 429. 

 t ' Scientific American ' (1879). 

 t 'Hedwigia,' xvii. (1878) 100. 



