BRIEFER ARTICLES 
REGENERATION OF BRYOPRHYLLUM CALYCINUM 
(WITH TWO FIGURES) 
In two articles on regeneration of Bryophyllum, Lors' bases his 
theories of inhibition and correlation in the regeneration of Bryophyllum 
upon the results of numerous experiments with severed leaves and por- 
tions of stems, and upon the negative results obtained with ‘normal 
plants.” After reading these articles, the writer recalled numerous 
instances of regeneration seemingly at variance with the experiments 
described. 
Experiments by Loes indicate that under suitable conditions whole 
leaves severed from the plant produce shoots from only a few notches. 
The writer has found the number of notches which produce shoots to 
vary from one or two to all of the notches, when whole leaves were 
placed in the moist air of a Wardian case, or, more frequently, on damp 
soil in the garden. The growth of all or many notches of whole leaves 
does not coincide with Lorp’s results, and furthermore is in direct oppo- 
sition to his theory of the flow of certain substances in the leaf deter- 
mined by the first notches which begin to grow, and the consequent 
inhibitory effect produced upon the growth of other notches. In view 
of Lorp’s results and theories, more striking even than the growth of 
many notches on severed leaves is the production of roots and shoots 
in the notches of leaves attached to growing plants. In introducing his 
subject, Lor asks, ‘‘Why does a leaf not form roots and shoots in its 
notches so long as it is in connection with a healthy plant?” (loc. cit. 
60:250). And again, under theoretical remarks, “ When a plant is nor- 
mal, it is almost or possibly absolutely impossible to induce the notches 
of a leaf which is connected with the plant to grow”’ (loc. cit. 60:274). 
Pot-grown plants of B. calycinum in the writer’s possession have fre- 
quently grown both shoots and roots from leaf notches while the leaves 
were in connection with the plant. Early in the spring of 1917 a large 
plant of Bryophylium (fig. 1) began to produce shoots from the leaves 
B, Jacques, Rules and mechanism of inhibition and correlation in 
regeneration of Bryophyllum calycinum. Bot. Gaz. 60:249~276. 1915; Fu 
xperiments on correlation of growth in Bryophyllumca lycinum. Bort. Gaz. 62:293- 
302. set 
tgt] [Botanical Gazette, vol. 65 
