THE SARCODINA 



241 



proper and the hypothallus the body may be drawn out into 



a stalk. 



The first events in the reproductive process are the formation of 



the protective and supporting elements 



of the sporangium. Over the surface 



of the lobe a membrane or envelope is 



secreted, the " peridium," and in the 



interior of the protoplasmic mass a 



network, or rather feltwork, of filaments, 



the " capillitium," is produced, of 



similar nature to the peridium, and in 



continuity with it ; peridium and 



capillitium contain cellulose or allied 



substances and the former may contain 



carbonate of lime in some species. 



During the formation of the pro- 

 tective peridium and the supporting 



capillitium the protoplasmic mass 



remains in the plasmodial condition, 



but when the accessory structures are 



completely formed the actual spore- 

 formation begins. According to recent 



investigations, spore-formation is initi- 

 ated by the degeneration of a certain 



number of the nuclei ; the nuclei that 



persist then divide by karyokinesis simultaneously throughout the 



whole plasmodium. The protoplasm then becomes divided up, 



directly or indirectly, into as many 

 masses as there are nuclei. The cells 

 thus produced, lying in the interstices 

 of the capillitium, become surrounded 

 each with a tough membrane, and are 

 the spores (Fig. 101). They are 

 liberated by bursting of the peridium, 

 and the hygroscopic properties of the 

 capillitium are the cause of movements 

 in it which assist in scattering the 

 spores. With the formation of the 

 spores the life-cycle has been brought 

 round to the starting-point that was 

 selected. The spores are scattered in 

 all directions by the wind, and 

 germinate in favourable localities. 



FIG. 100. Badhamia utricularis. 

 a, Group of sporangia, magni- 

 fied 12 ; 6, a cluster of spores ; 

 c, a single spore ; d, part of tho 

 capillitium containing lime- 

 granules : b and d magnified 

 170. From Lister. 



Flu. 101. Trichia varia : part of 

 a section through a sporan- 

 gium after the spores are 

 formed ; threads of the capil- 

 litium are seen in longitudinal 

 and transverse section. From 

 Lister, magnified 650 dia- 

 meters. 



The account given above may be taken as describing the typical series of 

 events in the life-history, which is liable to considerable variations in particular 



16 



