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siderable increase in thickness. There wasa thickening of the bark 
below and to the right of the direct line from above downwards, 
which indicated that the growth from the tree itself spread round 
the branch, but not immediately beneath it. The arrest of growth 
was shown by the enlargement of the branch just above the wound. 
‘his enlargement led at once to the idea that the cause of such 
enlargement was from the descent of material from above, and not 
from the rise of sap from below. “The rise of sap ”’ was a common 
expression, and was strictly true; for the rise of sap did take place, 
and the uninstructed would expect that swelling would take place 
below a vivisection, rather than above it ; bat it was clearly shown 
in this case that the growth of wood was from above down- 
wards, and not in the contrary direction. Leaving specimens No. 
1 for a time, he proceeded to show some of the deductions which 
might be made from No. 2. It was the main trunk of an arbor 
vite in which accident had produced a result similar to that which 
‘arose from design as shown on No. 1. He rescued it from a 
rubbish heap to which a gardener was about to consign it. 
The tree had grown for some years after a piece of tarred string had 
been tied round it. ‘This year the upper part of it died without 
assignable reuson ; but a section through the trunk explained the 
cause of death. ‘I'o make this clear he referred to the causes which 
give rise to the ascent of the crude and the descent of the elaborated 
sap. After stating that all living structures, avimal, as well as 
vegetable, have their first origin ina homogenous matter called 
protoplasm or bioplasm, which develops into cell life, he said the 
circulation in plants consisted\in the movement of a gelatinous 
matter slowly up one side of the cell wall across the end and down 
the other, generally taking somewhat of a spiral course. 
- The cell wall is lined by material in which chlorophyll granules 
are embedded. They form through the vital action which sets up 
the current, and it is continued by the chemical action which arises 
when the starch or sugar of the absorbed matter is changed into 
chlorophyll or some other product. ‘The movement is especially 
active in sunlight, which is absolutely required for the formation of 
the green matter of plant life. ‘This cell circulation is easily seen 
in various kinds of water-plants in which the cells are large. In 
Valieneria the chlorophyll granules move with the current. The 
rapidity varies with the activity of the growth of the plant. It is 
most rapid in warmth and sunlight, provided the heat is not 
excessive, but a temperature of 112 degrees Fahrenheit stops it in 
all plants that live in temperate climates. An electric current stops 
it for a time, and so does pressure. It can be seen in the 
labellum of an orchid, and in the hairs of many rapid-growing 
plants; also In lycopods and ferns; but a very little pressure 
stopped it. The circulation is limited to each cell. Itis established 
by the vital power which exists in the bioplasm, and it is then con- 
