XXII. 



THE HABITATS OF THE MYCETOZOA. 



By James Saunders, A.L.S., and E. Saunders. 

 Read at Watford, 10 th April, 1900. 



The study of the ilycetozoa has received a marked stimulus in 

 this oonntry during- thi' hist few years, chiefly tlirough the writhigs 

 and efforts of sucli t'ntliusiasts as Mr. Arthur Lister, the Kight 

 Hon. Sir Edward Fry, Mr. George Massee, and others. 



Consequent upon this the literature of the subject has lately 

 been considerably increased, but nowhere have we met with any 

 article which treats of these organisms from the standpoint in 

 which they are regarded in the present communication. 



In all catalogues and monographs of the Mycetozoa, it is 

 customary to mention the kind of vegetation on which they are 

 found, but nowhere, to our knowledge, are they grouped according 

 to habitat. It is almost superfluous to state that these creatures 

 are saprophytes. They are denizens of masses of decaying 

 vegetation, and frequent such situations as dead leaf-heaps, rotten 

 branches in damp woods, tree-stumps, old straw-heaps, and, much 

 more rarely, Sphagnum and humus. In the last mentioned, 

 Spiimaria alba, U.C., sometimes finds a congenial home. Although 

 Mycetozoa are sometimes found on living plants, in such cases they 

 have crept up from underlying decayed vegetation. A remarkable 

 exception is that of the plasmodium of Baclhaniia reticularis, which 

 often flourishes on living woody fungi, such as Stereum and Irpex. 



Until the spring of 1897 the researches of British observers were 

 almost entirely limited to rotten wood and decayed leaves, but from 

 that period till now considerable attention has been paid to the 

 possibilities of straw-heaps, especially those which have lain 

 undisturbed for several months. The results have been most 

 gratifying to those who have pursued these investigations. In 

 proof thereof it is sufficient to say that from April, 1897, till the 

 date of writing (October, 1899), this field of research has yielded 

 the previously undescribed species, Pht/sarum straniinipes, List., 

 and Didymium Trochus, List. ; and the first known British records 

 of Physarum didermoides, Host., variety lividum (var. nov.), Lister 

 (see 'Joum. Bot.,' vol. xxxvi, p. 161), of Badhamia ovispora, 

 Racib., and of Fuligo ellipsospora, List. 



Extended and frequent observations of the denizens of straw 

 heaps suggest another peculiarity in the occurrence of the 

 Mycetozoa, which is that certain species affect different strata of 

 the accumulated material. In illustration or confirmation of this 

 suggestion the following data are advanced : — 



Species usually found at or near the sui'face: — Physarum calidris, 

 List., P. didermoides, Host., and its var. lividum, List., Fuligo septtca, 

 Gmel., Didymium 7tiyrij)es, Fr., Spumaria alba, D.C. 



Species usually found at or above the line of saturation : — 

 Badhamia ovispora, Racib., Physarum compressicm, Alb. & Schw., 

 VOL. X. — PAUT V. i;^ 



