CHAPTER VIII. — MORPHOLOGY AND COURSE OF DEVELOPMENT. 447 



pear-shaped, conical at the smaller end and running out into a very strong flagellum ; 

 movement that of the swarm-cells of the Myxomycetes. The spores when they come 

 to rest creep about in the manner of the Amoebae.' Such is Haeckel's diagnosis. 

 This organism differs from the Myxomycetes chiefly in the absence of firm spore- 

 membrane, and in the circumstance that neither cell-nucleus nor division of the swarm- 

 cells has been observed. Myxastrum radians, Haeckel, also a marine form and dis- 

 tinguished by the presence of silica in the spore-membranes, appears to be nearly 

 allied to Protomyxa. 



Cienkowski's Vampyrellae are organisms with amoeboid movement which live 

 on Algae and Diatoms. Some like Vampyrella Spirogyrae and V. pendula suck the pro- 

 toplasm and chylorophyll-corpuscles from out of the living cells of species of Spirogyra 

 or Oedogonium, when they have pierced their walls, while V. vorax embraces the entire 

 cells of Diatoms, Desmids and similar forms with their pseudopodia, and absorbs them 

 into its own substance. In both cases the reception of a certain quantity of food is 

 followed by a period of rest, a smoothing of the surface of the body and the excretion 

 of a delicate firm membrane. In this state of rest the bodies which have been 

 absorbed are digested, that is are dissolved till there remain only comparatively minute 

 portions of the protoplasm which have assumed a brown colour, and in the case of 

 Vampyrella vorax of the membranes. Next follows the excretion of the undigested 

 substance from the living protoplasm, the division of the latter into usually 2-4 swarm- 

 cells and their escape from the membrane ; the two processes go on simultaneously, 

 the division being effected while ihe spores are escaping at 2-4 separate points. Then 

 according to J. Klein from 2-4 swarm-cells, seldom more, at once coalesce again 

 and form a plasmodium, which repeats the process just described of absorption of 

 food and subsequent formation of swarm-cells. In addition to this course of develop- 

 ment resting cysts may also be formed, in which case the body which has come to 

 rest inside the membrane excretes undigested remains of the food, and then without 

 forming swarm-cells excretes a new membrane. The subsequent fate of these cysts 

 is still unknown. Other transitory states of rest, as in the small cysts of the 

 Myxomycetes, may occur within the periodic course of development described above, 

 and no coalescence may take place, the cells passing singly through the swarming 

 state as above but not forming plasmodia. 



Cienkowski's Nucleariae appear to be just like the Vampyrellae in the 

 course of their development and in their manner of life. They are distinguished 

 from them by the presence of nuclei, which are said to be wanting in the Vampy- 

 rellae. Coalescence into plasmodia has not been observed in them, but it is not 

 excluded by the ascertained facts. 



Cienkowski's Monas Amyli has motile swarm-cells provided with two cilia, 

 and a number of these cells surrounding a starch-grain may coalesce into small 

 plasmodia. The plasmodium forms a membrane, and after its substance has increased 

 in size at the expense of the starch-grain it produces a large number of new swarm- 

 cells by simultaneous division. It is said also that a single swarm-cell may spread 

 itself round a grain of starch without uniting with others to form a plasmodium, 

 and thus become the starting-point of the development which was described above. 



An exactly similar course of development has been observed in Klein's 

 Monadopsis and Cienkowski's Pseudospora and Colpodella, except that the latter 



