12 



MYCETOZOA 



surface 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 ingested has been parted with 

 before leaving the wood, but it appears probable that their 

 food Mas absorbed in a state of solution. The plasmodium 

 of Badhamia utricular is is one of the very few we are 

 acquainted with that feed on living fungi. It is capable of 

 being cultivated without limit on Stereum hirsutum and allied 

 species, and can be observed under the microscope to dissolve 

 fungus hyphae as the hyaline border of a wave of the yellow 

 Plasmodium advances over them.* 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 as to cover 

 more than six square inches ; 

 the vigorous flow extended 

 over the meshes between 

 the veins and produced an 

 unbroken surface, f 



The mode in which the 

 multiplication of nuclei 

 takes place requires further 

 investigation. That they 

 sometimes divide by karyo- 

 kinesis is proved by the 

 case described in Journ. 

 Linn. Soc. (Bot.), xxix. 541. 

 In that instance a plas- 

 modium of B. utricularis 

 growing on Auricularia 

 mesenterica partly spread in 

 a network of veins over 

 two large cover slips. These 

 films were stained and mounted. In these two preparations 

 the nuclei are seen to be dividing by karyokinesis ; the stages 

 represented show the nuclear spindle, and the nuclear plate 

 divided and the two halves still connected by achromatic 

 fibres (fig. 5). Part of the same plasmodium spread over 

 another coverslip, and was killed and stained with the others. 

 The nuclei in this preparation have the appearance most 

 commonly met with, containing a central nucleolus, and with- 

 out any indication of karyokinetic division. The main body 



Fig. 5. — Badhamia utricularis Berk. 



Division of nuclei by karyokinesis in the 

 streaming Plasmodium. 



From a preparation stained in safranin, and 

 mounted in Canada balsam. 



Magnified 1200 times. 



* Lister, "Notes on Plasmodium of Badhamia and Brefeldia," Ann. Bot., ii. 13 (1888). 



t Constant ineanu has made a number of interesting experiments on the cultivation 

 of Mycetozoa with artificially prepared nutritive media; see his paper " Ueber die 

 Kntwicklungsbedingungen der Myxomyceten," Ann. Myc, iv. 49."> (1906). 



