Fig. 1 _b_. Single spore, x 500.

_Physarum mortoni_ n. s., p. 58.

Fig. 2. A group of sporangia, x 20.

Fig. 2 _a_. Capillitium, x 200.

_Physarum discoidale_ n. s., p. 74.

Fig. 3. A group of sporangia, x 10.

Fig. 3 _a_. A single spore, x 800.

_Didymium annulatum_ n. s., p. 125.

Fig. 4. Group of sporangia, x 15.

Fig. 4 _a_. Capillitium and spores, x 200.

_Oligonema brevifilum_ Peck, p. 280.

Fig. 5. Capillitium, x 800.

Fig. 5 _a_. The same.

Fig. 12 _b_. A single spore, x 800.

_Amaurochaete tubulina_ (Alb. & Schw.) Macbr., p. 150.

Fig. 6. Capillitium and spores, x 200.

Fig. 6 _a_. Spore, x 1200.

_Physarum brunneolum_ (Phill.) Mass., p. 58.

Fig. 7. Group of sporangia.

Fig. 7 _a_. The same, mature, dehiscence beginning, x 10.

Fig. 7 _b_. A single spore, x 800.

_Stemonitis uvifera_ n. s., p. 161.

Fig. 8. Colony, natural size.

Fig. 8 _a_. Capillitium and spore-clusters, x 30.

Fig. 8 _b_. Single spore-cluster, x 600.

Fig. 8 _c_. Spore, x 1000.

_Stemonitis trechispora_ Berk., p. 160.

Fig. 9. Fructification--natural size.

Fig. 9 _a_. Capillitium, branch and threads, x 20--the spores enlarged.

Fig. 9 _b_. Netted spore, x 1000. Masking as an amaurochete; _A.
trechispora_ perhaps; compare 11, etc., below.

_Stemonitis flavogenita_ Jahn, p. 169.

Fig. 10. A group of sporangia, x 3.

Fig. 10 _a_. Capillitium showing columella-tip, x 50.

Fig. 10 _b_. Spore, x 1200.

_Stemonitis trechispora_ (Berk.) Torr., p. 159.

Fig. 11. A group of sporangia, x 3.

Fig. 11 _a_. Diagram of a single sporangium, a less rudimentary
specimen, x 40.

Fig. 11 _b_. Capillitium enlarged to show branching columella, x 40.

Fig. 11 _c_. A single spore, x 1200.

_Arcyria pomiformis_ (Leers) Rost., p. 255.

Fig. 12. A globose colony of sporangia, x 10; var. _conglobosa_.

Fig. 12 _b_. See under 5, above.

[Illustration: PLATE XX]

EXPLANATION OF PLATE XXI

Brefeldia maxima (Fr.) Rost., p. 154.

A typical, beautiful aethalium, about natural size.

[Illustration: PLATE XXI]

EXPLANATION OF PLATE XXII

_Brefeldia maxima_ Rost., p. 154.

Fig. 1. Plasmodium active; climbing the stump.

Fig. 2. Same plasmodium urgent; moving at the rate of 2 cm. per hour.

From photo-prints by Mr. W. A. Seaman and Mr. John T. Reeder, Mich. The
figures are about one-sixth the natural size of the object. See plate
preceding for the mature phase of this species, na