276 
Mac Dougal, 
pressure which would be set up by tliis solution would be about 35 
atmospheres. A number of plants grown as aquatics withe mature form 
of finely divided filamentous leaves, and others wliich had been culti- 
vated as terrestrials and formed the mature type of finely dissected 
leaves were placed in the solution in 1904. The filamentous aquatic 
leaves were quickly killed, and the plants bearing them were checked 
and showed no marked activity of any kind during the few weeks the 
experiment was continued. The individuals taken from terrestrial 
conditions showed a marked difference in reaction. The finely divided 
leaves were not killed, but the terminal buds which produced them 
became inactive. At the same time lateral or axillary buds on the 
terrestrially grown stems underwent rejuvenescence, beginning with the 
formation of broadly laminar leaves, which merged in a series in which 
incision and division became more marked. The preparation was taken 
down before filamentous threads were produced. 
The continuation of the observations upon material from the 
original introduction resulted in a long vegetative series. Some of tliis 
material had been carried to the Coastal Laboratory at Carmel, and 
was being cultivated as aquatics with the mature filamentous type of 
leaf-divisions in 1912. Three of the plants were placed in a glass disli 
containing 1000 ccm of water and 5 gram potassium nitrate on August 2. 
The following entries are taken directly from my notebock: 
“Early in September it was seen that the series of leaves included 
forms which passed by gradual stages into organs with divided laminar 
segments with fewer incisions until finally organs were produced in 
which the indentations were entirely marginal and the small but rela- 
tively broad laminae were those of the nepionic type, which thus had 
come about by gradual stages rather than as an abrupt reaction.” 
It was thus demonstrated again that in Neobeckia as in Sium and 
Proserpinaca the addition of such compounds as potassium nitrate to 
a water culture in which aquatic individuals were growing “resulted in 
the production of primitive leaf-forms in a simplifying series rather 
than as abrupt appearange following rejuvenescence.” 
The interpretation of these reactions involves the whole question 
as to the nature of the physical changes underlying rejuvenation, and 
no pretence is made that the facts cited above solve the main problem. 
The general trend of the evidence afforded by the behavior of Neobeckia 
for ten years however may be best apprehended when the facts in 
question are considered in totality. 
