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and other metals that the richest tints in coloured glass are produced. If gold 
could always be used, it would produce a very rich carmine or crimson tint ; 
but it is too expensive, and metals are used producing tints approximating 
to it, like the older and richest tones of stained glass, as found in our old 
cathedrals, and which tones our artists now imitate with very great success. 
The reason why I asked if the ciliary motion, referred to by Mr. Brooke, is 
mechanical, was because, if the matter is positively dead, I do not see how 
any movement can arise unless in the same way that a piece of paper in the 
air is moved about, mechanically, in consequence of its shape. With reference 
to Professor Kirk’s paper, I agree with what has already been said as to its 
great value. I think it is as carefully written, although a shorter paper, than 
any of the others with which Professor Kirk has hitherto favoured us. There 
is, however, one part of it to which possibly our opponents will take excep- 
tion, and therefore, perhaps, Professor Kirk will not be sorry to have it 
noticed, though it looks almost hypercritical to point it out. In the 11th 
paragraph Mr. Kirk says : — 
“ When Professor Bennett says that ‘no one can doubt that an aggrega- 
tion ot molecules produces a vibrio, which, at first motionless, has contractilFty 
communicated to it, and thereby lives,’ he forgets that if the molecules are 
self-moving they are alive ; he makes the strange blunder of imagining that 
life is not as essential to the self-aggregation of the molecules as to the 
contraction of the vibrio.” 
I fancy that that “ self-aggregation ” Professor Bennett would say arises 
merely from the attraction of the particles to one another. So that the result 
would be that in time there would be an aggregation of particles which would 
be inseparable except by some chemical means, producing isolation. There 
is one other part of the paper where a similar remark occurs, and where our 
opponents would argue that these things were merely drawn together, and 
then began to live. They do not explain whether the cells are of different 
characters or not— perhaps they may be male and female, and so produce 
generation. That is a very remarkable fact which Professor Kirk calls 
attention to— that boiling does not destroy the life of these animalcules ; 
but we have plenty of illustrations of an analogous kind to enable us to 
understand this. A few years ago people would have said it was almost 
impossible to stand the heat of a Turkish bath, where you may have boiling 
water alongside of you. Chantrey also went into his oven where he baked 
his models at a heat of some 300 degrees ; and there was a famous “ fire- 
eater ” at one time who used to exhibit, and have ducks roasted by his side 
in an oven, and afterwards ate them, and he suffered nothing from this heat. 
It is not only true that boiling will not destroy life in these animalcules, but 
we have also learnt from Dr. Carpenter that you cannot even squeeze the 
life out of them ! Dr. Carpenter, as is well known, has recently been 
exploring the ocean-bed of the Atlantic. Formerly it was given out among 
scientific men, that animal life could not exist at a depth of 300 yards, or 
less than a quarter of a mile ; but now we find that they live at a depth of 
three or four miles down, where the pressure is so great that the tubes of the 
