8 THE JOURNAL OF BOTANY 



scattered threads ; these branch upwards in a tree-like maimer, and 

 are attached to the upper sporangium-wall by slender tips, and to 

 the lower wall by broad bases. Ttie capillitium of the new form is 

 very profuse, and consists of slender, usually straight threads con- 

 nected together by a few anastomosing branches, and attached to 

 the sporangium-wall above and below by narrow points. The 

 colour varies in both species, but in D. di forme it is generally 

 purple-brown ; in D. comatum it is almost always colourless, as far 

 as can be ascertained from the comparatively limited material at 

 hand. Beside the Lyme Regis gatherings a small specimen was 

 obtained from near Luton in February, 1893, with profuse colour- 

 less capillitium and pale spores, precisely similar to those of the 

 sporangia first collected on the Lyme undercliff. 



No specimens have been found with capillitium intermediate in 

 character between these strikingly diverging forms. In order to 

 ascertain by cultivation whether the peculiar features of D. comatum 

 would remain constant, the following experiment was made : — 

 On March 9th, 1899, spores were sown in a hanging drop. In 

 about six hours every spore appeared to have germinated, and the 

 preparation teemed with swarm-cells. Three other cultures were 

 put down in watch-glasses on March 10th, and at the same time 

 spores were scattered over a piece of scalded blotting-paper, together 

 with some boiled cress-seeds. As a check experiment, spores of 

 D. di forme, gathered with D. coynatum, were also sown on similarly 

 prepared blotting-paper. I may mention that in cultivations of 

 D. di forme from spores sporangia almost invariably begin to appear 

 in about a fortnight ; on one occasion, when the spores were sown 

 with seeds of Plantago lanceolata, sporangia formed in eight days. 

 In the case of this check experiment well-formed sporangia appeared 

 in about fifteen days from the date of sowing, with characteristic 

 coarse capillitium, which varied in quantity and was reduced in the 

 very small sporangia to one or two threads, or was altogether wanting. 

 This corresponded with former experience, when cultivations of 

 this species have been carried on for many generations in suc- 

 cession. It was not until forty days after the spores of D. comatum 

 were sown — that is to say, on April 19th — that the first minute 

 sporangia appeared in the blotting-paper preparation ; others con- 

 tinued to develop until April 30th, when thirty- eight sporangia 

 could be counted ; but they were so small that they could hardly be 

 seen without the aid of a lens. Every one examined, even the most 

 minute, had profuse slender colourless capillitium and pale spores 

 of precisely the same character as that of the parent sporangia. In 

 the watch-glass experiments no Plasmodium formed until May 2nd, 

 or fifty-three days after sowing, and this occurred in only one of 

 the glasses ; it increased to more than a millimetre across, and 

 appeared to be quite healthy, when an accident prevented further 

 observation. 



As far as it goes, this culture points to a specific difference 

 between D. diforme and D. comatum,, but in the face of the straw- 

 ■ yard gathering before referred to it seems safer to mark the new 

 form as T). diforme var. comatum. 



