MR. A. J. EWART ON ASSIMILATORY INHIBITION. 427 
formation of starch can apparently be detected if, as rarely 
happens, the chlorophyll grains assimilate for longer than 4 
hours, but the grains are excessively minute and still more doubt- 
fully the result of the assimilation of the chlorophyll grains after 
isolation. 
In Zlodea canadensis the externally isolated chlorophyll grains 
show no power of assimilation. If leaf strips are plasmolysed 
in strong sugar solution and then examined in 15 per cent. to 
20 per cent. sugar solution 4- Bacteria, the shrunken cell-contents 
do not perceptibly re-expand, but show a distinct though not 
strong evolution of oxygen. In some cells, at one end or corner 
2 or 3 chlorophyll bodies or even single ones may be isolated, 
and from these a weak but distinct evolution of oxygen can be 
detected if the plasmolysed bodies of the neighbouring cells are 
sufficiently distant, and if the chlorophyll grains are adhering to 
the upper side of the cell-wall. In some cases such isolated 
chlorophyll grain or grains can be seen to have a little plasma 
associated with them, or to have plasmatic connections, but in 
other cases appear to be perfectly free from plasma and to be 
without any fibrillar connection with the rest of the cell con- 
tents, and nevertheless retain the power of assimilating and 
evolving oxygen. 
It appears, therefore, that in certain cases an isolated chloro- 
phyll grain can continue to assimilate, but is incapable of an 
independent life, ceasing to assimilate, and dying within a few 
hours after removal from the parent cell. 
The above fact does not in any way support the hypothesis 
that the chlorophyll bodies of higher green plants are phylo- 
genetically to be regarded as endophytic symbiotic algal cells 
which have completely or almost completely lost their autonomy, 
but is rather comparable with similar cases known in animal 
physiology (Frog’s heart or sartorius or gastrocnemius muscle), 
where an isolated organ of considerable physiological complexity 
may remain living and functionally active for many hours, or 
even a couple of days, after removal from the parent body. 
Cases in which in adult cells, after a destruction of the “ pri- 
mary” chlorophyll grains, a new formation of “ secondary ” 
chlorophyll grains takes place are not definitely established. 
Thus Schimper has shown that, in the winter browning of ever- 
greens, it is only when the chlorophyll bodies remain intact that 
LINN. JOURN.—BOTANY, VOL. XXXI. 2 
