6 04 Notes . 
is conveyed when the annular space of such double-walled vessels is 
filled with air V 
It is to be noticed that in Professor Dewar’s first experiment the 
seeds were practically in a vacuum. It is obvious, from what has 
been quoted above, that this would help them to retain their heat. 
Any hesitation in accepting the results of the experiment on this 
ground is, however, swept away by the second experiment, in which 
the seeds, with absolutely no protection at all, were actually soaked 
in liquid hydrogen for six hours. The extremity of caution can 
hardly resist the conclusion that they must have been brought to the 
same temperature. 
Professor Dewar finds ‘ that silica, charcoal, lampblack, and oxide 
of bismuth all increase the insulation to four, five, and six times that 
of the empty vacuum space.’ It might possibly be worth while to 
try how far a packing of small air-dry seeds would compare, say, 
with charcoal. And this would in some degree be a measure of the 
thermal transparency of seed structures. 
Professor Dewar suggested to me that I should supplement this 
statement by some remarks on the physiological bearing of the ex- 
periment. This has already been discussed by Messrs. Brown and 
Escombe, and there is perhaps little of moment to add to their 
conclusions. 
The real interest of the whole investigation obviously lies in the 
question how far it modifies our conceptions of the nature and pro- 
perties of living matter. Protoplasm, whatever its source, has physical 
properties and an ultimate chemical composition which are practically 
uniform. This uniformity, however, overlies a potential diversity 
which is not to be measured. Such diversity cannot be accounted 
for by any purely physical conceptions, as physical conceptions are 
understood. 
We not merely know the ultimate constitution of protoplasm, but 
we also know a good deal about its proximate constitution. Yet the 
properties of living protoplasm are very far removed from the mere 
sum of those of its constituents, and no light can be derived with 
respect to them in this direction. And what we know about the 
constituent bodies themselves is at present not a little obscure. They 
belong, as it were, almost to the fringe of possible chemistry, and 
almost elude the methods of chemical research. But they, complex as 
1 On Liquid Air as an Analytic Agent, Roy. Inst., Apr. i, 1898, pp. 7 and 8. 
