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flow that was pouring into it from the network of veins you see 
below—channels is a better word than veins, for there are no 
vein walls—the whole mass is in motion, but it is in these vein: 
like branching and constantly shifting channels that the main 
rhythmic streaming takes place. 
A method for the preparation of pure sclerotium I have lately 
adopted may perhaps be worth mentioning. A portion of the 
sclerotium of Badhamia utricularis, soaked in water, is placed 
on a pileus of Séereum on a dinner plate under a bell-jar; it 
revives in the course of a few hours, and the plasmodium spreads 
over the fungus; as it grows we add fresh S/evewm every morn 
ing and the exhausted pieces are cleared away. In the course 
of a fortnight or so the cultivation is thus led round the plate 
inacircle. When the plasmodium has increased sufficiently, the 
bell-jar is removed and the growth is left exposed for two days ; 
then folded strips of wet blotting paper are laid with one end 
resting on the pile of Stereum and the other end lying on the 
clean part of the plate ; these are covered by a plate of glass to 
prevent rapid evaporation, but the pile is left uncovered ; the 
plasmodium, attracted by the moisture, leaves the S¢erewm and 
spreads over the wet blotting paper, on which it discharges its 
refuse matter. When it has spread sufficiently the plate of glass 
is removed and it is left to dry and form the clean sclerotium 
such as you see here. If a bit of the blotting paper one-eighth 
of an inch square thus coated with dry sclerotium is soaked in 
water and placed on a thin cover ship inverted over a moist 
chamber, such as a ring of four thicknesses of wet blotting paper 
on a glass slide, the plasmodium will revive in a few hours and 
the streaming can be watched under the microscope. 
The causes that produce the change of the plasmodium into 
sporangia are not always easy to trace ; want of nourishment 1s 
perhaps the principal one. I the plasmodium spreading over 
the wet blotting paper just described were allowed to remain 
moist, sporangia would form in four or five days, but if kept 
supplied with Szereum it would continue to grow for months. 
On the other hand Didymium difforme may §° through the 
whole cycle from spore to sporangium in about a fortnight. 
When the change comes, the whole of the plasmodium partir 
pates in the formation of the fruit ; a part is applied to the a 
struction of the hypothallus and stalk, part to that sate 
sporangium-wall and capillitium, and the remainder is divide 
up into spores. e * 
As already stated, at the time of the bipartition of the ae 
cells the nuclei divide by karyokinesis ; during the active = “ 
the plasmodium, when of course they multiply enormous se 
great number of observations with different species lead to we 
conclusion that they divide by constriction, oF simple division. 
