26 VARIATION, DISTRIBUTION, AND EVOLUTION OF THE GENUS PARTULA. 
The character of the food of Partule is a matter of considerable interest, in 
view of the theoretical possibility that differences in the vegetation of separated 
valleys might be adduced to account for the diverse characteristics of the snails in 
such different localities. When the facts are examined, however, this possibility 
is ruled out. Confining our attention to the low arboreal species, and disregarding 
those of the ground and of the highest tree-tops, we have several independent series 
of data that justify the statement given. In the first place, it is clear that the 
snails do not feed on the living tissue of the plants upon which they are found, 
because the organisms may be present in numbers on a perfect unmutilated leaf, 
and because no leaves occur that display alterations saving such as are made by 
insect larve. Secondly, the animals go to the ground to feed, as described in the 
foregoing paragraphs. Thirdly, the stomach-contents of active and newly killed 
snails comprise no fresh vegetable material, but only the rasped fragments of decay- 
ing woody and fleshy plant tissues. Again, animals that were feeding under obser- 
vation in nature avoided the living parts of plants and restricted themselves to 
decaying leaves and wood. Finally, the specimens that were brought back to the 
laboratory ate moist dead leaves with avidity; only when very hungry did they eat 
the whiter and firmer portions of lettuce and cabbage leaves. In transporting them 
from the field, they consumed great quantities of wet paper, which, to all intents 
and purposes, is wood pulp. Dall has suggested that in the case of Achatinellide 
decaying vegetation is eaten for the sake of the fungi that grow in and upon it. 
Whether or not the same is true for Partule, the fact remains that the nurse-plants 
upon which Partule are found during the day do not seem to have any effect upon 
the specific or varietal characters displayed by these animals. We would scarcely 
expect that this would be so, when representatives of three distinct species may be 
sealed up on a single leaf of caladium, plantain, or Dracena. 
The food of ground-snails seems to be the same as that of the lower arboreal 
types. Towhat extent that of the P. attenuata series may differ or may agree remains 
for further determination; but, by analogy, it would consist of what the snails might 
find on the woody twigs and branches of the tree-tops. 
