424 BOTANICAL GAZETTE [NOVEMBER 
contain a gel held in solution as a hydrosol by the action of a peptizator. Puri- 
fied tannin solutions do not tan, and the more “‘impure” the solution the 
better the tanning effect. Watery tanning solutions on standing in the air 
undergo changes that increase their tanning value, owing to the formation of 
an insoluble product that becomes peptized. 
MOELLER finds a similar situation exists in the artificially prepared tan- 
ning solutions. In chinon tanning solutions the chinon takes the place of a 
peptizator, while hydrochinon is the peptized gel. In the mineral tanning solu- 
tions an insoluble metallic hydroxide is peptized into the solution condition 
by the peptizing action of the acid salt solution. According to MOELLER’S 
view, the properties of a tanning extract depend upon the equilibrium between 
the peptizator and the peptized substance, and the character of the leather 
depends upon the nature and quantity of the peptized gel that is taken up by 
the hide fibers—F. E. DENNY 
Taxonomic notes.—Miss GILKEY” has published a revision of the Tuberales 
of California, preceded by an account of the distribution of truffles in California, 
their economic importance, and their morphology and phylogeny. Accom- 
panied by very full discussion, 11 genera are presented, including 32 species, 
the largest genus being Tuber, with 12 species. A new genus (Hydnotryop- 
sis) and 15 new species are described, distributed among the following genera: 
Hydnocystis, Genea (3), Hydnotrya, Tuber (6), Piersonia, Geopora (2), and 
Hydnotryopsis. ‘ 
West™ has described a new genus of mycorrhizal fungi associated with 
the roots of the various genera of Marattiaceae. He names it Stigeosporium, 
and regards it as of special interest inasmuch as it produces “‘under natur. 
conditions distinct reproductive bodies within the tissues of the host root.” 
WILLIAMS” ea published a list of Peruvian mosses based upon two collec- 
tions. It includes 71 species, among them 6 new species in the following genera: 
eg psa Globubina, T. ortals, Grimmia, Bryum, and Hygrohypnum.— 
, Heten Marcaret, A revision of the Tuberales of California. Univ. 
Calif. Publ. Bot. 6:275-356. pls. hie 916. 
™ West, CyriL, Stigeosporium M. saa gen. et sp. nov. Ann. Botany 
30:357- Igt6. 
TLL1aMS, R. S., Peruvian mosses. Bull. Torr. Bot. Club 43:323-334- 
pls. 17-20. ae. 
