ADDRESS. 1 5 



of spherical cells, each included in a delicate membranous wall, and 

 •when they fall into water the wall becomes ruptured, and the little cell 

 creeps out. This consists of a little mass of protoplasm with a round 

 central nucleus, enclosing a nucleolus, and with a clear vacuole, which 

 exhibits a rhythmically pulsating movement. The little naked spore thus 

 set at liberty is soon seen to be drawn out atone point into a long vibratile 

 whip-like flagellum, which by its lashing action carries the spore from 

 place to place. After a time the flagellum disappears, and the spore may 

 now be seen emitting and withdrawing finger-like pseudopodia, by means 

 of which it creeps about like an Amoeba, and like an Amoeba devours 

 solid particles by engulfing them in its soft protoplasm. 



So far these young amoeba- like Myxomycetas have enjoyed each an 

 independent existence. Now, however, a singular and significant pheno- 

 menon is presented. Two or more of these Myxamcebse, as they have been 

 called, approach one another, come into contact, and finally become com- 

 pletely fused together into a single mass of protoplasm, in which the 

 components are no longer to be distinguished. To the body thus formed 

 by the fusion of the Myxamcebas the name of ' plasmodium ' has been 

 given. 



The plasmodium continues, like the simple amcebiform bodies of 

 which it is composed, to grow by the ingestion and assimilation of solid 

 nutriment, which it envelopes in its substance ; it throws out ramifying 

 and inosculating processes, and finally becomes converted into a proto- 

 plasmic network, which in its turn gives rise to spore-cases with their 

 contained spores and thus completes the cycle of its development. 



Under certain external conditions the Myxomycetas have been observed 

 to pass from an active mobile state into a resting state, and this may 

 occur both in the amcebiform spores and in the plasmodium. When the 

 plasmodium is about to pass into a resting state, it usually withdraws its 

 finer branches and expels such solid ingesta as may be included in it. Its 

 motions then gradually cease, it breaks up into a multitude of polyhedral 

 cells, which, however, remain connected, and the whole body dries into a 

 horny brittle mass, known by the name of ' sclerotium.' 



In this condition, without giving the slightest sign of life, the sclero- 

 tium may remain for many months. Life, however, is nob destroyed, its 

 manifestations are only suspended, and if after an indefinite time the 

 apparently dead sclerotium be placed in water, it immediately begins to 

 swell up, the membranous covering of its component cells becomes dis- 

 solved and disappears, and the cells themselves flow together into an active 

 amoeboid plasmodium. 



We have already seen that every cell possesses an autonomy or inde- 

 pendent individuality, and from this we should expect that, like all living 

 beings, it had the faculty of multiplying itself, and of becoming the parent 

 of other cells. This is truly the case, and the process of cell-multiplication 

 has of late years been studied, with the result of adding largely to our 

 knowledge of the phenomena of life. 



