PHYCOMYCES NITENS. 23 



The inner hiyer is sonit'whtit tiiickor than the outer, hotli boinj>- of an 

 even thickness except for a little space around the sporang-iopjiore 

 where the inner one thins out and disappears. Whether or not tliis 

 is honioloo-ous witii the "collar" of Piloholus, the writer can not be 

 certain. 



The spores are set free bv the ))urstino' of the sporanoiuni wall, 

 witiiout its being- thrown off. ^Vhether or not the inner layer ot" the 

 wall swells bv the absorption of water and bm-sts the outer layer the 

 writer has not determined. The writer has never found this inner layer 

 on sporano-ia as voung- as that shown in PI. I. tio-. 5. nor in the walls 

 of the mycelium. 



The ripe spores as they escape from the ruptured sporangia are 

 mostly ovoid in sliapt' and of varying sizes. Their walls are marked 

 with longitudinal ridges, as may be seen in PI. Ill, tig. 14. 



PHYCOMYCES NITENS Kunze. 



Unlike Rhizojym^ the sporangiophores of Phycomijces are "borne 

 singly, springing directly from the mycelium. When the sporangio- 

 phore is yet only a few millimeters long, the apex b(>gins to swell out 

 into a sporangium in the same manner as that described for Rluzopns 

 nigricans. As the sporangium enlarges the sporangiophore elongates, 

 pushing up the former farther and farther from the surface of the 

 substratum. The spores are formed when the sporangiophore is 

 about 2 cm. long, and it is then that the sporangium has its maximum 

 diameter. 



As shown in PL IV, fig. 15, there is the same streaming of cytoplasm 

 and nuclei up the sporangiophore and out toward the periphery of the 

 sporangium as in Bhhojym nigricanx. 



As can be seen by a comparison of PI. IV, tig. 15, with PI. I, tig. 5, 

 the cytoplasm in the young sporangium of Phycomyces is more coarsely 

 granular than that of RJdzopus and takes the stain much more deeply. 



The most noticeable difference between the young sporangium of 

 Fhycomyces and that of Ehizopusis that in Phycoinyccs there are many 

 more large round vacuoles which, as they move outward toward the 

 periphery of the sporangium, become filled with a visible content. 

 (PI. IV, fig. 15.) This content appears in sections stained with the 

 triple stain as a 1)luish homogeneous body of the same shape as the 

 vacuole but somewhat smaller in diameter, lying in the middle of the 

 vacuole, with a clear zone between it and the vacuolar membrane. 

 (Pis. IV and V, figs. 15 to 22. ) This content begins, not as a very minute, 

 sharply-staining body which grows larger and larger in diameter, but 

 as a faintly-staining mass which, as it grows older, becomes more 

 dense and takes the stain more strongly. In the youngest stage it 

 appears quite as large in proportion to the size of the vacuole in 

 which it lies as when it becomes older. (PI. IV, fig. 16.) It forms in 



