HIDDEN MABKIAGES 671 



breaks up into few or many (according to species) smaller masses which 

 form into sporangia. A crust forms around the sporangium and the enclosed 

 portion breaks up into spores ; but prior to this a system of delicate threads 

 is constructed, forming a network in which the spores are held. This is 

 known as the capillitium. There are also in some species free threads called 

 elaters, spirally twisted and hygroscopic. As the sporangium ripens and 

 dries, the investing membrane breaks up by shrinking and the spores are 

 only held together by the capillitium network. The elaters expand and 

 contract, their movements throwing the spores out through the meshes 

 of the capillitium. Many of them have granules of calcium carbonate 

 in the walls of the sporangia and as knots on the capillitium threads. The 

 same substance appears in the plasmodium. 



The period of nutrition corresponds with the amoeboid state that is, the 

 swarm-cell and the plasmodium. As swarm-cells they are negatively helio- 

 tropic they avoid 

 the light and retire 

 into the darkness 

 of rotten wood and 

 decaying leaves; 

 but in the plasmo- 

 dium stage their 

 heliotropism be- 

 comes positive 

 they stream out to- 

 wards the light in 

 order to form their FIG. 720. DEVELOPMENT OF A MYXOMYCETE. 



SDOranfia On the I - ne u PP er row shows : 1, a spore ; 2, the contents of the same emerging as a swarm-cell 



& with a nucleus ; 3, the same with nucleus, vacuole, and llagellum ; 4, the swarm-cell 



exterior Of their has assumeci tne amoeba form. Below is a portion of plasmodium, and to the right 



a sporange. All diagrammatic. 



habitat. The 



swarm-cells are also positively hydrotropic they move from dry to moist 

 places; and both swarm-cells and plasmodium are trophotropic they move 

 towards nutrient substances. 



De Bary, to whose researches much of our knowledge of the Class is due, 

 decided in favour of their animal nature on account of the formation of a 

 plasmodium by the aggregation of the swarm-cells. But although he said 

 their place was " outside the limits of the vegetable kingdom," he continued 

 to include them in his botanical works. What has always appeared to 

 us a strong argument against their being driven out of the vegetable 

 kingdom is that their exhibition of animal traits is restricted to their 

 earlier stages of development. The test of their real nature should be 

 applied to their ultimate condition and their mode of reproduction, both 

 of which are essentially vegetable. The catching and digesting of Bacteria 

 is indicative of animal nature, it is true, but what about the trapping and 

 digesting of animal food by the Sundews, the Butterworts, Bladderworts, 



