MR. A. J. EWART ON ASSIMILATORY INHIBITION. 428: 
Chara. Of these, the latter is only very slight and does not, as 
a matter of fact, perceptibly affect the assimilatory powers of the 
cell. In the former case the inability to assimilate is, where the 
browning and decolorization is complete, readily explained by 
supposing that the absorption of the necessary energy cannot 
take place, assimilation returning as soon as the necessary pig- 
ment is formed and the necessary connection established, which 
is often whilst the plant is still quite yellow. What is certain is- 
that the chlorophyll bodies, being living plasma organs, are, like 
all living plasma, liable by various disturbing influences to an 
arrest of certain functions, in this case more especially of assi- 
milation. Such functional derangement is possible with and 
without visible alteration in either the colour or structure of 
the chlorophyll grain. In this respect the absorption or non- 
absorption of light is of only secondary importance, for chloro- 
phyll grains of normal appearance and showing normal absorption 
may be temporarily inactive. 
The question as to whether an isolated chlorophyll body can 
assimilate and evolve oxygen is, in this connection, of much 
interest. Engelmann * states that single isolated chlorophyll 
bodies continue, if exposed to light, to assimilate and evolve 
oxygen, but gives no further details beyond stating that it is 
shown by the chlorophyll grains of many plant-cells, and that in: 
water the chlorophyll grain swells and bursts and the evolution 
of oxygen ceases. In one case given, viz. Hydra viridis, we 
have to do not with chlorophyll grains but with Zoochloranthellz, 
modified endophytie algal cells, according to Brandt T. Haber- 
landt f, however, found that in Funaria hygrometrica isolated 
chlorophyll grains continue to assimilate and evolve oxygen 
(Bacterium method) in a 25-per-cent. solution of cane-sugar, but 
does not state how long the power of assimilation is retained. 
His experiments are also open to the serious objection that in a 
25-per-cent. solution of sugar B. Termo is plasmolysed and 
almost entirely ceases to move. The explanation probably is 
that, in making the preparations, the sugar solution was diluted. 
* Engelmann, “ Neue Methode zur Untersuchung der Sauerstoffanscheidung 
pflanzlicher und thierischer Organismen,” in Bot. Zeit. 1881, p. 446. 
+ Brandt, in Monatsber. d. Berlin. Akad. 1881, p. 388. 
i Haberlandt, ‘Ueber die Beziehungen zwischen Function und Lage des 
Zellkernes,’ 1887, p. 117. 
