8 



INTRODUCTION. 



with this statement ; the cases of hybridism referred to by Mr. 

 Massee in his Monograph* appear to require confirmation. 



The food of plasmodia is often easy to determine. Those which 

 live among dead leaves spread with veins which are brown from 

 the incorporation of decayed vegetable matter, and when the refuse 

 is discharged they become white or yellow, according to the species, 

 shortly before they form into sporangia. The plasmodium of 

 Badhamia panicea thrives on the inner bark of felled elms, and 

 is difficult to discern on the red-brown substratum owing to the 

 broken 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 Amaurochcete atra 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 

 splenclens may also be found 

 emerging from the sawn sur- 

 face of fir stumps, which show 

 no sign of decay, and covering 

 an area of six to seven square 

 inches. Whatever solid matter 

 these plasmodia may have in- 

 gested has been parted with 

 before leaving the wood, but 

 it appears more probable that 

 their food was absorbed in a 

 state of solution. The yellow 

 plasmodium of Badhamia 



FIG. 5. BADHAMIA UTRICULAEIS Berk. utriculciriS is the only One 



Division of nuclei by karyokinesis in the we are acquainted With which 

 streaming plasrnocuum. PI i- p i 



From a preparation stained in safranin, and leedS Oil living tllllgl and IS 



mounted in Canada balsam. rartnlYIp nf bpino- nnH-ivnfprl 



Magnified 1200 times. .ctpau ing 



without limit on Stereum 



hirsutum and allied species ; it can be observed under the micro- 

 scope to dissolve fungus hyphre as the hyaline border of a wave 

 of plasmodium advances over them.f The growth of this species 

 is often very rapid ; a plasmodium measuring about a square inch 

 in area on a large pileus of Auricularia mesenterica has been seen 

 to increase during twenty hours so a* to cover more than six 

 square inches ; the vigorous flow extended over the meshes between 

 the veins and produced an unbroken surface. 



The multiplication of nuclei which takes place in such a 

 growth as this, where we may assume, from numerous observa- 

 tions, that they have increased at least sixfold, requires further 

 investigation. That they sometimes divide by karyokinesis is 



* Mass., J/OM., p. 15. 



f Lister, " Plasmodium of Badhamia," etc.. Annals of Botany, vol. ii.. 

 1888, p. 13. 



