10 INTRODUCTION. 



In a few instances a large nucleus encloses two nucleoli, and 

 occasionally there are appearances which strongly suggest that 

 simple division of a nucleus is taking place. Some days later, 

 when the plasmodium had ceased to feed, and was collecting 

 together to form into sporangia, stain ings showed the nuclei more 

 equal in size, measuring 4 to 5 /x in diameter. This experiment 

 may be taken to add materially to the negative evidence, to say 

 no more, that under some conditions the increase in the number 

 of the nuclei is produced by simple division. 



The plasmodium of the exosporous C eratiomyxa issues from the 

 interior of rotten wood to form cushion-like heaps which rapidly 

 extend into columnar or branching sporophores. As the stream- 

 ing movement common to both divisions of the Mycetozoa is not 

 described by Famintzin and Woronin in their valuable paper on 

 Ceratiomyxa before alluded to, the following observations may be 

 given. Hounded cushions of plasmodium were placed on a cover- 

 slip, supported at the margins by wet blotting-paper, and were 

 thus enclosed in a moist chamber. The plasmodium spread in a 

 film over the glass, and here eventually an abundant growth of 

 spores was produced. At the earliest stage that could be ob- 

 served under the microscope the plasmodium was seen to be 

 sharply differentiated into two elements a hyaline part which 

 ultimately forms the principal constituent of the gelatinous 

 column, 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 Endospovece. 



The Sclerotium. Superficial 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. When the plasmodium of Badhamin 

 utricularis is dried, the streaming movement gradually ceases, 

 and the granular particles collect in clusters, surrounded by a 

 border of hyaloplasm ; the refuse matter is thrown out, and a 

 membranous cyst-wall forms round each cluster of granules, 

 which also includes 10 to 20 nuclei; the cysts become agglomer- 

 ated into thick masses 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 amoaboid movement, it is probable that this movement takes 

 place throughout the mass. The sclerotium of this species can 

 be revived after preservation in a dry state for three years, by 



* Lister, " On Flasmodium of Badhamia and Brefeldia," Ann. Sot., vol. ii., 

 1888, p. 13. 



