physarum] ph ysaraceae 7 1 



characters : from P. nutans by the abundant lime-knots and darker 

 spores ; from P. vemum the sessile forms are separated by the more 

 compressed sporangia and darker spores; from P. didermoides by the 

 presence of refuse matter in the stalk and by the single sporangium - 

 wall ; from P. sinuosum by the darker spores and shorter plasmodio- 

 carps. For other allied species, see P. straminipes, P. connatum, and 

 P. reniforme. Much difference is found in the size and roughness of the 

 spores in sporangia from the same cultivation ; in some they measure 12 

 to 15 fx, and are strongly spinulose, while in others they are smoother, 

 and average 9 to 1 1 /«- diam. The spines are usually evenly distributed, 

 but are sometimes grouped in patches separated by narrow smoother 

 tracts, which gives the spore a facetted appearance, but this feature is 

 never so marked as in P. straminipes. The granules in the sporangium- 

 wall frequently coalesce into vitreous superficial scales or coarse 

 particles, and those in the lime-knots become transparent and lose their 

 granular character ; this feature is also met with in other species of 

 Physarum. In preparations in water of highly calcareous sporangia 

 part of the solid matter is found to dissolve, and, on drying, to crystallise 

 on the slide in particles resembling those described. A cultivation from 

 an extensive growth of plasmodium exhibited the forms a, {$, and y in 

 the development of the sporangia : 



a. Sporangia obovoid or reniform, laterally compressed, on short 

 black or grey stalks, or sessile. 



(3. Sporangia obovoid or reniform, on white stalks 0"5 mm. long. 



y. Plasmodiocarps lobed and confluent. 



The specimens named P. nephroideum Rost. (Strassb. Herb.) are 

 the form a. The type of P. candidum Rost., from Juan Fernandez 

 (K. 510), is the form ft ; in some of the sporangia the lime-knots- 

 coalesce to form a central mass ; that of P. Phillipsii Balf., from 

 Phillips' Herb., shows the forms a and y ; and that of P. lividum var. 

 conglobatum Rost., from Ceylon, no. 55 (K. 1244), is the form a with 

 short black stalks ; that of P. affine Rost., from Cuba, no. 907 (K. 1350), 

 is the form R with white stalks. The specimen named Didymium 

 botryoides Berk, in Herb., from New Zealand (K. 1523) — named by 

 Massee D. radiatum B. & C. — is the form a. D. pruinosum Berk. & Curt., 

 from Cuba (K. 1515), given by Rostafinski as a synonym for P. neph- 

 roideum (Rost., App., p. 5), is the form a. The type of Didymium 

 glaucum Phill. from California is form a ; the sporangia are either on 

 short black stalks or sessile. 



Hob. On dead leaves, twigs, straw, etc. — Bedfordshire (B.M. 1238) ; 

 Hertfordshire (B.M. 1239); Shrewsbury (B.M. 115); Birmingham 

 (B.M. 1240) ; Forres (K. 106) ; Sweden (B.M. 2195) ; near Paris (B.M. 

 2197) ; near Berlin (B.M. 1050) ; Italy (B.M. 423) ; Portugal (B.M. 

 2196) ; Ceylon (B.M. 419) ; Australia (K. 1314) ; New Zealand 

 (B.M. 2198); Philippine Islands (B.M. 2041); Japan (B.M. 2199); 

 Colorado (B.M. 2200) ; Philadelphia (B.M. 2201) ; Dominica (B.M. 

 1651a) ; Brazil (B.M. 1779). 



38. P. connatum Lister {non Ditm.) Plasmodium white. 

 Sporangia stalked, scattered and free, or grouped in clusters 

 of two or more, globose, turbinate or reniform, greyish- 

 white, 0*5 to 07 mm. diam. ; sporangium-wall membranous 

 with clustered deposits of lime-granules, rarely iridescent 

 and almost free from lime. Stalk stout, furrowed, dark or 



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