CH.VIII. MORPHOLOGY AND COURSE OF DEVELOPMENT. MYXOMYCETES. 423 



In the creeping movement the swarm-cell lies on the firm substratum, and 

 either advances in one direction with a vermicular movement and with the cilium 

 stretched out in front ; or it assumes a roundish form and thrusts out processes, 

 pseitdopodia, in every direction and then draws them in again. The two kinds of 

 movement, the hopping and the creeping, often pass into one another, and may 

 frequently be observed alternating with one another in the same individual with 

 apparently alternating retraction and protrusion of the cilium. Swarm-cells with 

 purely amoeboid motion have been unnecessarily distinguished by the name of 

 myxamoebae. 



The swarm-cells multiply by bipartition, which, to judge by the vast numbers 

 sometimes obtained from a sowing of the spores, may be repeated through several 

 generations. The movement becomes more sluggish before division, the swarm-cell 

 contracts into a spherical form and the cilium and the vacuoles disappear. This is 

 followed by the appearance of an annular constriction in the middle which speedily 

 becomes deeper and in a few 

 minutes divides the body into two 

 spherical halves which at once re- 

 sume the characters of motile swarm- 

 cells. The nucleus becomes indis- 

 tinct during the division but does 

 not entirely disappear, and it may 

 be presumed from analogy that it 

 also is divided. Exceptions to the 

 rule here laid down have been ob- 

 served in Chondrioderma difforme 

 and Didymium praecox, in which 

 the protoplasm was divided inside 

 the spore-membrane and issued 

 from it in the shape of two swarm- 

 cells, about as often as it escaped 

 from it in the form described above. 

 Famintzin and Woronin too found 



that the protoplasmic body which came out of the spore in the Ceratieae divided 

 by successive bipartitions into eight portions, which separated from one another 

 as swarm-cells provided with cilia. 



SECTION CXIX. The further development of the swarm-cells consists in their 

 uniting together to form the large motile protoplasmic bodies, which Cienkowski 

 named plasmodia. The course of events in this process was directly and completely 

 observed under the microscope by Cienkowski in Didymium leucopus, Fr., 

 Chondrioderma difforme (Didymium Libertianum) and Perichaena liceoides, Rost. 

 (Licea pannorum, Cienk.). A number of less perfect observations of Lycogala, 

 Fuligo and Stemonitis which have been communicated to me, and the resemblance to 

 one another of all fully formed plasmodia, justify the assumption that the course of 

 development is essentially alike in all Myxomycetes. 



The phenomena' directly observed in the development of plasmodia are of the 

 following kind (Fig. 183). In a few days after the spores are sown the divisions 



FIG. 183. Chondrioderma difforme. i ripe spore. 2 the same ger- 

 minating. 35 swarm-cells. 6, 7 the same in the amoeboid state. 8 two 

 amoeboid swarm-cells in close contact. 9 the same when coalesced to 

 form the beginning of a plasmodium. 10 three swarm-cells in contact with 



one another. 



of them after coalescence, the third still fr< 



young plasmodium, which has taken up two spores into its substance. 

 After Cienkowski from Sachs' Lehrbuch. Magn. 350 times. 



