PROCEEDINGS OF THE SOCIETY. 803 



divisions, and finally fuse together, forming an amoeboid jelly-mass or 

 Plasmodium. 



Usually, the amoeboid stage is aquatic only at the outset. The 

 Plasmodia, often so small as to be scarcely perceptible, attain in some 

 species dimensions of several inches. They spread over decomposing 

 vegetable substances, on which they feed, and so increase in bulk. The 

 veins of their fan-like and net-work extensions exhibit reversing currents 

 of the interior plasm. These currents, or streamings, are caused by 

 pressure and suction, probably originating in rhythmic dilatations and 

 contractions of slow respiration. Apparently the functional energy by 

 which the plasmodia breathe is thus converted into the flowing impulses 

 by which they move. After a while, they creep from damp to drier 

 spots, and gather up for spore-formation. For this purpose, plasmodia 

 occupying the interstices of rotting wood come to the surface. 



The aerial, or dry phase, is a process of rejuvenation by purification. 

 The congested plasm relieves itself by excreting its undigested contents, 

 and the rejected substances are deposited in various forms of hypothallus, 

 stalks, columellas, sporangia walls, capillitia, or spore-cases. The secretion 

 of the spore-cases by the plasm is the last act of purification. Practically 

 the whole of the plasmodium breaks up into spores, and the spherical 

 shape and uniform size of the spores in each species is a striking geo- 

 metrical expression of the balanced condition of the purified plasm, 

 governed by energies radiating from nuclear centres, which are equally 

 distributed throughout the mass. The life-cycle recommences with the 

 emergence of the swarm-spores into water, after the fine, dry powdery 

 spores have been liberated from the sporangia, by wind, rain, or other 

 means. 



The entire life-history is thus essentially a series of alternating phases, 

 in which numbers of plasm-specks (swarm-spores) blend into a larger 

 jelly-mass (plasmodium), which breaks up into multitudinous spores, and 

 so on, endlessly. 



The question of the sexuality of Mycetozoa is a very obscure one. 

 In all three phases there are nuclear divisions, and in the maturer stages 

 the nuclei multiply greatly ; but there also appear to be nuclear fusions, 

 followed by reduction divisions, especially in the stage immediately prior 

 to formation of spores. Whether such fusions are sexual is by no means 

 clear. 



The specimens under the Microscopes are all British, and illustrate 

 only the aerial phase of the life-history. In most instances the sporangia 

 are intact, and contain spores. In regard to the other specimens, it must 

 be remembered that, as the spores have been dispersed, the structure 

 which remains, however curious or beautiful, is but the lifeless memorial 

 of biological processes, which have passed on to repeat themselves in a 

 new generation. 



The President said they would look forward to examining Mr. Hilton's 

 slides of these very primitive organisms, which were in many ways pecu- 

 liarly fascinating. He had always thought that the formation of the 

 Plasmodium was in itself a rudimentary sexual process. 



The thanks of the Society were voted to Mr. Hilton for his interesting 

 exhibit and communication. 



