1905] McCALLUM—REGENERATION IN PLANTS 247 
activities, presumably those concerned with growth, is necessary; 
and it has been shown above that however this may act on the buds 
below, it is not through any disturbance created in nutritive or water 
relations. 
GOEBEL (5) has shown that if in Bryophyllum all the buds on the 
stem are prevented from growing by encasing them in plaster, the 
growing points on the leaves develop. HERING (7) showed that the 
small cotyledon of Streptocarpus would develop both structurally 
and functionally into the large one, if the latter were prevented 
mechanically—by plaster—from growing. WINKLER (19) has found 
that by a similar treatment of the leaf blade of Cyclamen the new 
leaf-like structures that develop when the blade is removed will arise 
from the margin of the petiole. He leaves us in doubt as to whether 
he selected leaves that had entirely ceased growth before his experi- 
ments began. He thinks that the regeneration is due to the inter- 
Tuption of one or more of the functions; either respiration, transpira- 
tion, or photosynthesis. My results show that for Phaseolus and 
Salix cessation of neither transpiration nor photosynthesis will cause 
regeneration. Respiration is checked in the hydrogen, but what 
other changes may be involved it is impossible to say. 
On those plants whose growing tip soon ceases activity and dies, 
as Syringa vulgaris, I have not been able to induce the axillary buds 
to develop by removing the apical part of the shoot. In all of many 
cases tried, however, in which the terminal growing points continue 
their activity during the growing period, their early removal was 
followed by the sprouting of latent buds below (jig. 2). This is 
true even in those plants whose annual shoots are without branches, 
and in the axils of whose leaves the buds cannot be seen even with 
the aid of a lens. 
Lack of space prohibits a detailed description of these experi- 
oe, and only the results need be given. In the majority of cases 
tis the buds near the apex that start (fig. 3), but occasionally almost 
€very one on the shoot starts; and in one case, ‘on a shoot of Salix, 
only those at the base started. The young shoots were either cut 
off and the base placed in water, or else they were left attached to 
the plant. If the tip is cut off and also all the leaves, the buds 
develop. Or if the tip is removed and the shoot placed in the moist 
