` 
A24 MR. A. J. EWART ON ASSIMILATORY INHIBITION. 
down to 15 per cent. or 20 per cent., in which B. Termo con- 
tinues to move actively. 
The method adopted is to cut sections with a sharp razor in 
‘sugar solution, when, on removing the sections, many uninjured 
chlorophyll grains are left behind. To this fluid Bacteria, taken 
fresh from a pure culture on the point of a sterilized platinum 
wire, are added, and the cell is then closed. The less manipu- 
lation the better, no pressure from the cover-glass is allowable, 
air-bubbles must be totally absent, the Bacteria must be from 
young and perfectly pure cultures, the sugar solution filtered 
and sterilized, and the leaves carefully washed and brushed in 
sterilized water. Otherwise, preparations from moss-leaves often 
contain unicellular alge, which naturally show active assimila- 
tion, and which are in some cases rather like chlorophyll grains 
and apt at first to be mistaken for them, being surrounded by a 
-cell-wall of extreme tenuity. When we consider to what severe 
treatment the chlorophyll grains hust necessarily be subjected 
in order to procure its isolation, and under what abnormal con- 
-ditions it then is, it is not surprising to find that the majority 
of the plants experimented with, including Chara, Nitella, Oxalis, 
Ilex, &c., gave negative results. In Ozalis the acidity of the 
liberated cell-sap probably injuriously affects the chlorophyll 
grain, and this may to a greater or less extent often be the case. 
The cases in which definite results were obtained are arranged 
for convenience in tabular form :— 
Catharinea | Weak assimilation in 10 p. c. sugar, stronger in 15 p. c. 
undulata, In 1 to 3 hours the evolution of oxygen begins to weaken 
and in 3 to 5 hours ceases. In 1 p. c., 2 p. c., 3 p. c., 
4 p. c., or 5 p. c. KNO, solution no power of assimila- 
tion is shown. 
Funaria In 10 p. e. and 15 p. e. many chlorophyll grains show 
Aygrometrica. weak but distinct assimilation, which in 1-2 hours 
| weakens and in 3-5 hours ceases. Similar results with 
| the chlorophyll grains of the sporogonium, but being 
smaller the evolution of O is correspondingly weaker. 
[Any spores present show a distinct evolution of oxy- 
| gen when in the young green chlorophyll containing 
condition, but this becomes weaker as the spores grow 
older, and the chlorophyll alters and finally ceases. } 
Dicranum In 5 p. c. and 10 p. c. cane-sugar very weak assimilation 
scoparium. is shown in many chlorophyll grains, but in 1 hour 
this begins to weaken, and in 2-3 hours none is per- 
ceptible. 
