_Tubifera ferruginosa_ watery white, scarlet, brown, almost black _Cribraria dictydioides_ clear dark green _Cribraria tenella_ watery, dark plumbeous, bronze _Cribraria cuprea_ red _Arcyria nutans_ white _Arcyria denudata_ watery white, then flesh-color _Arcyria cinerea_ grey, then white _Trichia varia_ colorless, then white h. In a few instances references to illustration do not find place in connection with the descriptive matter. One phase of _Physarum albescens_ is figured on Pl. III.; _Mucilago_ will be found portrayed on Pl. VII.; _Physarum viride_ on Pl. VIII. j. The group before us has research possibilities not a few. The question of their nutrition and its limits in respect of variety, is yet to be solved. From present indications all that can be said is to the effect that a pabulum similar in variety, no doubt meets the needs of many species. Whether in artificial culture a single base as gelatin or agar would suffice for all or several is yet to be discovered. Whether a species brought from spore to maturity on artificial diet would conform in any reasonable way to our dim concept of its identity is also, it would seem, a problem. The variation in the field would seem to make it doubtful. From the table immediately preceding it is plain that there is place for doubt. Color it is surmised is of itself everywhere incidental; the structure, which maintains identity or the reverse, lies deeper, although color may be none the less, in some way a resultant, and therefore in so far a reliable taxonomic guide. The treatment of our subject so far by no means exhausts the possibilities of even the simpler phases of microscopic study. We have endeavored to appreciate the work of those who hand us the literature of the group, and to recognize what such keen-eyed men have seen; but in our western and southern forests there are probably double as many species, as species go, as we have listed. The entire group is, as it would seem, in highest measure worthy of investigation and comprehension, and should it at any time prove that to such accomplishment the present volume may have been in any smallest way contributory, the author's satisfaction will be complete indeed. FOOTNOTES: [40] Farr. _Cell-division in Pol. Mother-cells, Cobaea scandens, Bull. Tor. Bot. Cl._, Vol. 47, pp. 325-38. INDEX NATURAL ORDERS, etc. CRIBRARIALES, 199 EXOSPOREAE, 18 LYCOGALALES, 232 PHYSARALES, 22 PHYTOMYXINAE, 17 STEMONITALES, 148 TRICHIALES, 236 GENERA ALWISIA, 208 _Alwis_; personal. AMAUROCHAETE, 148 [Greek: amauros], dusky, and [Greek: chaite], hair. Gr. ARCYRIA, 247 [Greek: arkyon] a net. Gr. BADHAMIA, 313 _C. D. Badham_; personal. BREFELDIA, 154 _O. Brefeld_; personal. CALONNEMA, 266 [Greek: kalos], beautiful, and [Greek: nema], a thread. Gr.