1900] PERENNIAL HERBS 175 
in the seed before germination (fig. 3). In the following years 
this migration of the plant downwards continues in a similar 
way. The alternation of roots mentioned above shows itself 
from the second year onward. 
While the occurrence on one and the same plant of two 
kinds of roots differing in form and function is not very rare, the 
formation of these at different times, as in Arisaema, has so far 
been found only in a few species. I have noted the same fact, 
for instance, in Allium ursinum L., Fritillaria Meleagris L., Scilla 
bifolia L., and some other monocotyledons. 
Arisaema triphyllum (L.) Torr. resembles perfectly A. Dra- 
contiwm in the behavior of the underground organs. 
The contraction of the roots seems to play a great part in 
another American species of Araceze, in Spathyema foetida (L.) 
Raf. In this plant a stem-tuber is formed, which grows vertically 
upwards, dying off gradually at its lower end. This tuber 
attains 10° in length and 5°™ in thickness, and comprises the 
Products of several years. It forms yearly about fifteen roots 
hear its upper end. These grow obliquely downwards, tapering 
toward the tip, and produce from their thin end portion lateral 
rootlets of the first and second orders. They live several 
years, so that about sixty to seventy of them are found in 
ame Pent. All the roots are contractile, and apparently prevent 
gs emerging of the tuber from the ground, This has been 
i also by Foerste, who found the seedlings germinating 
ma of the surface of the ground and the top of Be 
ease C Several inches below the surface. I found saa 
Serminating on the surface of the soil and the growing 
pm OF the tuber in several larger specimens at a depth of 
about Ioc™, 
Just the 
(L.) Covi 
ining 3° in height and 2™ in diameter. All its roots, 
in a ring-like belt, are more or less contractile 
basal portion, which becomes transversely 
HAAG as they grow steeply downwards they are enabled 
same phenomenon may be observed in Hypoais hirsuta 
