1895.] Vegetable Physiology. 851 
(3). Plectrillum (nov. gen.)* Spore-bearing rods clavate. 
(4). Arthrobactrillum (nov. gen.)* With arthrospores. 
Sup-FamiLy BAcTRIDEI. 
Motile, with diffuse flagella. 
(1). Bactridium (nov. gen.) Spore-bearing rods cylindrical. 
(2). Clostridium(Prazm. pro. parte.) Spore-bearing rods fusiform. 
(3). Plectridium (nov. gen.) Spore-bearing rods clavate. 
(4). Diplectridium (nov. gen.) Spore-bearing rods dumb-bell shape. 
(5). Arthrobactridium (nov. gen.)* With arthrospores. 
According to the author, 8 or nearly one-half of these so-called genera 
are founded on purely theoretical considerations, while there is some 
doubt as to whether there are any known species to go into two others. 
These pseudogenera are here indicated by asterisks. 
—Erwin F. SMITH. 
The Mushroom Gardens of South American Ants.—Ever 
since the appearance of that wonderfully interesting book, The Natu- 
ralist in Nicaragua, it has seemed probable that the leaf-cutting ants 
do actually grow fungi for food, and use the countless thousands of leaf 
fragments which they drag into their nests for the same purpose that a 
gardener uses dung. Belt ascertained that the leaves were never used 
for food, found the fungus in every nest, observed the solicitude of the 
ants when it was disturbed, and in various particulars carried his in- 
quiry as far as it was possible to do by simple observation. It remained 
for Alfred Möller, a young German, the nephew of Dr. Fritz Müller, 
and the pupil of Dr. Oscar Brefeld, not only to confirm Belt’s surmise 
by close observation and exact experiment, but also to add greatly to 
our knowledge of the habits of these curious little gardeners and of the 
nature of the fungi they cultivate. These observations and experi- 
ments are embodied in Die Pilzgärten einiger südamerikanischer 
Ameisen (pp. VI, 127, Figs. 4, Pl. VII), which forms the 6th part of 
Professor Schimper’s Botanischen Mittheilungen aus den Tropen, Jena, 
1893. Möller’s observations were made at Blumenau, Brazil, where 
he remained two years. The journey was made under the auspices of 
the Royal Academy of Sciences, of Berlin, whose wisdom in making 
this expenditure of a few thousand marks has certainly been more than 
justified by the outcome. During the course of the investigation sev- 
eral hundred ant nests were examined, these ants belonging to three 
genera, viz.: Atta (4 sp.); Apterostigma (3 sp.), and Cyphomyrmex (2 
sp.) All are zealous cultivators and eaters of fungi, but the ants of 
