382 



BOTANY 



PART I 



and animals, and have in consequence also been termed Mycetozoa or 

 Fungus - animals. They are represented by numerous species, and 

 are widely distributed over the whole earth. In the first instance 

 the behaviour of the most comprehensive Order, the Myxogasteres, 

 may be considered. In their vegetative condition these Slime Fungi 

 consist of naked masses of protoplasm, the PLASMODIA, containing 

 numerous small nuclei but utterly devoid of chlorophyll. Glycogen 

 occurs as a reserve substance, while starch is not found. The plasmodia 

 (Fig. 4) are found most frequently in woods, upon soil rich in humus, 

 upon fallen leaves, and in decaying wood. They creep about on the 

 substrata, changing their form at the same time, and thrust out 

 processes or pseudopodia, which may in turn coalesce. They feed 

 by taking up solid particles and reach favourable situations for their 



nutrition owing to their capacity 

 of chemotactic, hydrotactic, and 

 negatively phototactic move- 

 ments. At the period of spore- 

 formation the plasmodium 

 creeps out from the substratum 

 towards the light and air, and, 

 after coming to rest, is con- 

 verted into a single or into 

 numerous and closely contiguous 

 fructifications, according to the 

 genus. On the periphery of each 

 fructification an outer envelope 



FIG. 311. Ripe fructifications, after discharge of the T>T?RmTTTTu ia WTYIO^ wlii'la 



spores. A, Stemonitis fnsca (x 10); B, Arcyria < 

 punicea(x 12); C, Cribraria rufa (x 32). internally the Contents of the 



fructification separate into 



SPORES, each of which is provided with a nucleus, and enclosed by an 

 outer wall. In many genera, part of the internal protoplasm within the 

 SPORANGIUM or spore-receptacle is utilised in the formation of a CAPIL- 

 LITIUM (Figs. 311 A, B, 312 B\ consisting of isolated or reticulately- 

 united threads or tubes. Upon the maturity of the spores, the 

 peridium of the sporangium becomes ruptured, the capillitium expands 

 (Fig. 311 B\ and the spores are dispersed by the wind, aided by the 

 hygroscopic movements of the capillitium. In the case of the genus 

 Ceratiomyxa, the process is somewhat simplified, as the fructification 

 is not enveloped by a peridium, and the spores are produced on the 

 surface at the ends of short stalks. 



The germination of the spores (Fig. 313, Chondrioderma) takes place in water 

 or on a wet substratum. The spore wall is ruptured and left empty by the escaping 

 protoplast. After developing a flagellum or CILIUM as an organ of motion, the 

 protoplast swims about in the water, being converted into a SWARM-SPORE (Fig. 313 

 e-g) which resembles certain Flagellata, with a cell-nucleus in its anterior or ciliated 

 end, and a contractile vacuole in the posterior end of its body. Even within the 



