A Monograph of the Myxogastres. 9 



purple with cellulose reagents. After the vegetative mycelium 

 has acquired a certain amount of reserve material, one or more 

 of the thickest portions give origin to yet thicker branches 

 which grow erect ; each erect branch at length becomes dilated 

 into a large sphere at its apex ; into this sphere a considerable 

 amount of protoplasm, obtained from the vegetative mycelium, 

 becomes concentrated, and retained by the development of a 

 transverse septum at the base of the sphere where it passes into 

 its support. After these preliminaries, the reproductive phase 

 may be said to commence, the protoplasm undergoes differenti- 

 ation, resulting in the separation of lime which appears in the 

 form of a thin frosting outside the wall of the sphere or 

 sporangium ; another portion of the protoplasm becomes differen- 

 tiated into the broadly elliptical conidia or spores ; while a third 

 portion of the protoplasm, which may be considered as of no 

 value in the process of spore-making, remains in the form of 

 very thin, irregular strands in what may be termed the 

 intercellular spaces between the spores. Most species of the 

 Phycomycetes and Mucorini pass through the above phases 

 during their development, differing in minor points, as form of 

 conidia, presence or absence of lime on sporangia, &c. The 

 above description covers many points in the development of a 

 typical member of the Myxogastres. The latter differ at the 

 starting-point in the first product of germination, being more 

 motile than in Mucor, after coalescence of the cells to form a 

 plasmodinm; the latter usually behaves somewhat similar to 

 the mycelium of Mucor, advance of the mass being effected by 

 the protrusion of long tapering strands which at some distance 

 behind the tips coalesce to form a dense, irregular network; 

 every portion of a plasmodium, even the thinnest outlying 

 strands, are furnished with a distinct, thin, yielding membrane, 

 analogous at least to the membrane called the cell- wall, protect- 

 ing the protoplasm in the Mucor mycelium ; the two membranes 

 agree in origin, being secreted by the protoplasm ; both become 

 blue with iodine, and pale dirty brownish-violet with " chlor-zinc 

 iodide." The reproductive phase consists in the conversion of 

 certain portions of the protoplasm into erect sporangia with the 



