PLASMODIA 



«3 



sultry summer mornings, there issues from old tan in the pits, or in green- 

 houses and hot-beds, a bright yellow, apparently liquid substance, which collects 

 in the form of large flat cakes, occasionally pounds in weight and some 

 centimetres thick, and the surface of which is sometimes smooth, sometimes 

 covered with numerous branched excrescences. In greenhouses it may happen 

 that this substance {jEthaliiim sepiicum) creeps up the stems of plants a 

 metre high and more, in the form of thin threads, and becomes collected 

 above on large leaves as thick cakes the size of the hand. If large quantities 

 of tan, in which the yellow clumps of ^thaliwn are already recognisable, are 

 placed on a dish early in the morning, and covered with a bell-glass and 



Fig. 80— a Plasmodium of Didyminm leucopus (after Cienkowsky, X 350). B fructification ai Arcyria incarnata, stiU 

 closed ; C the same after rupture of the wall / and extension of the capillitium cp (after De Bary, X 20). 



allowed to stand in a room, the movements of the JEthalium may be observed 

 for days together. Occasionally it creeps over the edge of the dish on to the table, 

 and spreads on this, forming threads and broad cakes with undulating or moss-like 

 surfaces, until it finally becomes rigid and breaks up into innumerable small 

 cells. If wet glass slips are placed vertically in the tan already containing the 

 JEthalium, it creeps up upon these ; and if brought under the microscope the form 

 and movement of the substance may be more exactly observed (Fig. 80). There 

 remains no doubt whatever that we have here to do with a structure which resembles 

 in every detail the circulating protoplasm in living plant-cells, only its mass is re- 

 latively extraordinarily large. 



Besides the internal mobility of these free masses of protoplasm, by means of 



