14 



MYCETOZOA 



the streaming movement common to both divisions of the 

 Mycetozoa is not described by Famintzin and Woronin in their 

 valuable paper on Ceratiornyxa* the following observations 

 may be given. Rounded cushions of plasmodium were 

 placed under a cover-slip supported at the margins by wet blot- 

 ting-paper, and were thus enclosed in a moist chamber. The 

 Plasmodium spread in a film over the glass, and eventually 

 developed into healthy sporophores. At the earliest stage 

 that could be observed under the microscope the Plas- 

 modium was seen to be sharply differentiated into two elements 

 —a hyaline part which ultimately forms the principal con- 

 stituent of the gelatinous column of the young sporophore, 

 and the granular protoplasm containing numerous small 

 nuclei. In the film on the cover-glass the granular substance 

 spread in a network of veins through the hyaline portion. 

 Through these veins the protoplasm streamed in rhythmic 

 flow, first in one direction and then in the other, at the same 

 intervals of time as in the Endosporeae. 



The Sclerotium. — Plasmodia may pass into the resting 

 stage or sclerotium, and this change may be induced by 

 exposure to dry air. In some cases, however, it occurs when 

 water and apparently food material are present, and the cause 

 for the change is then difficult to discover. As the Plas- 

 modium of Badhamia utricularis becomes dry, the streaming 

 movement gradually ceases, and the granular protoplasm 

 becomes aggregated in discrete masses surrounded by hyalo- 

 plasm ; the refuse matter is thrown out, and a membranous 

 cyst-wall forms round each mass, which also includes 10 to 

 20 nucbi ; the cysts become packed into thick agglomerations 

 of irregular shape, drying to a horny consistence.! The 

 changes of outline seen in the maturing sclerotia cannot be 

 merely the effect of shrinking from drying, and as under the 

 microscope we frequently observe the cysts along the margin 

 of a forming sclerotium creep among each other with amoeboid 

 movement, it is probable that the change in shape of the mass 

 may thus be accounted for. The sclerotium of this species 

 can revive after preservation in a dry state for three years, on 

 being placed in water. Recently formed sclerotium resumes the 

 streaming condition in a few hours, but after remaining dry for 

 more than a year it requires to be kept Avet for some days 

 before the movement begins ; the cyst-walls are then absorbed, 

 and their contents coalesce. It frequently happens that parts 

 of old sclerotia are incapable of resuscitation, but they afford 

 a pabulum for the newly awakened plasmodium, through 

 whose veins the cysts may be seen to be carried along 

 and broken up. The sclerotium of Didymium squamulosum 



* " Ueber Ceratium hydnoides," M£m. Acad. P<5tersbourg, xx. 3 (1873). 



t Lister, '* Notes on Plasmodium of Badhamia and Brefeldia" Ann. Bot., ii. 13 (1888). 



