INTRODUCTION 11 



different parts ; it is generally abundant at the advancing 

 margin. The hyaloplasm appears to be a more firm condition 

 of the protoplasm assumed when exposed on the surface. 

 How far it may have a relation to the rhythmic streaming of 

 the plasmodium, or what causes that movement, has not been 

 ascertained. The track where a plasmodium has passed is 

 marked by a large residuum of substance free from granules 

 and charged with refuse matter. 



The description given above applies to plasmodia which 

 creep over dead leaves or the surface of logs or woody fungi. 

 Those which inhabit the interior of rotten wood usually 

 emerge only at the time of spore-formation, and then appear 

 as cushion-like masses or as scattered globules. The plas- 

 modia of the Calcarineae contain granules of calcium carbonate 

 (designated " lime "). The granules vary in abundance in 

 different species, being small and inconspicuous under the 

 microscope in some, while in the opaque white plasmodium 

 of Diderma hemisphericum they appear like crowded glass beads 

 2 /x or more in diameter, and greatly impede the streaming 

 movement. The colour of the plasmodium is usually either 

 white, yellow, or pink ; in some cases it is purple or green. 

 It is generally constant in each species. An exception occurs 

 in Trichia decipiens, which usually rises from rotten wood in 

 rosy pink globules, but frequently the plasmodium is watery 

 white ; the two colours are not met with together in the 

 same growth, but the sporangia from each are identical in 

 all characters. Dianema depressum has, as a rule, a white 

 Plasmodium, but occasionally pink. 



De Bary's statement that " union never takes place between 

 plasmodia of different species "* is fully borne out by the 

 experience of others, and no satisfactory evidence to the 

 contrary has been obtained. 



The food of plasmodia varies according to the species. 

 Those which live among dead leaves spread with veins which 

 are brown from the incorporation of decayed vegetable 

 matter, and the refuse is discharged shortly before they form 

 into sporangia. The jslasmodium of Badhamia panicea 

 thrives on the inner bark of felled elms, and is difficult to 

 discern on the red-brown substratum owing to the fragments 

 of bark with which it is densely charged ; it becomes pure 

 white by the rejection of enclosed matter before fruiting. 

 Occasionally the question of food is somewhat obscure : for 

 example, the plasmodium of Amaurochaete fuliginosa rises 

 in cushions from half an inch to two inches in diameter from 

 the hard and apparently sound wood of Scotch firs ; that of 

 Stemonitis splendens may also be found emerging from the sawn 



* De Bary, I.e., 426. 



