GENERAL BIOLOGY. 17 



Figs. 17 to 88.— In the following flgnres, lia, denotes atrial Iiyph»; sp, sporangium; 



zy^ sygospore; ex, exosponum; my, mycelium; mc, mucilage; d, columella; en, 



eudogoniala. 

 Fig. 17.— Spore-bearing hypliae of Mucor, growing from liorse-dnng. 



Fiii. 1 ■ The same, teased out with needles (A, 4). 



Figs. 19, 20, 21.— Succes.=iive stages in the development of the sporangium. 



Fig. 32.— Isolated spores of Mnoor. 



Fig. 23.— Germinatmg spores of the same mold. 



Fig. 24.— Successive stages in the germination of a single spore. 



Figs. 25, 26, 27.— Successive phases in the conjngative process of Mucor. 



Fig. 28.— Successive stages observed during ten hours in the growth of a conidiophore 



of Penicillium in an object-glass culture-tD, 4). 



or tubules, flUed with, protoplasm and invested by cellulose 

 walls, across which transverse partitions are found at regular 

 intervals, and in which vacuoles are also visible. « 



The spores, when growing thus in a liquid, gives rise to up- 

 ward branches (aerial hyphen), and downward branches or root- 

 lets {submerged hyphoe). These multitudinous branches inter- 

 lace in every direction, forming an intricate felt-work, which 

 supports the green powder (spores) which may be so easily 

 shaken oflE from a growing mold. In certain cases the aerial 

 hyphse terminate in tufts of branches, which, by transverse 

 division, become split up into spores (Conidia), each of which 

 is similar in structure to a yeast-cell. 



The green coloring matter of the fungi is not chlorophyl. 

 The Conidia germinate under the same conditions as Torula. 



Mucor mucedo. — ^The growth and development of this mold 

 may be studied by simply inverting a glass tumbler over some 

 horse-dung on a saucer, into which a very little water has been 

 poured, and keeping the preparation in a warm place. 



Very soon whitish filaments, gradually getting stronger, ap- 

 pear, and are finally topped by rounded heads or spore-cases 

 {Sporangia). These filaments are the hyphoe, similar in struct- 

 ure to those of Penicillium. The spore-case is filled with a 

 multitude of oval bodies (spores), resulting from the subdivision 

 of the protoplasm, which are finally released by the spore-case 

 becoming thinned to the point of rupture. The development 

 of these spores take place in substantially the same manner as 

 those of Penicillium. Sporangia developing spores in this fash- 

 ion by division of the protoplasm are termed asci, and the spores. 

 ascospores. 



So long as nourishment is abundant and the medium of 

 growth fluid, this asexual method of reproduction is the only 

 one ; but, under other circumstances, a mode of increase, known 

 as conjugation, arises. Two adjacent hyphse enlarge at the ex- 

 tremities into somewhat globular heads, bend over toward eadi 

 2 



