220 



KNOW Li.nc.i:. 



JlSE, 1012. 



(if tlie case. SiiHu-iciit tlwit tlic iikiss is now tht- 

 only nnknowii whicli prevents us from solving the 

 prolileni. and this is deduced liy the apphcation of 

 Stoke's law, which gives an expression for the velocity 

 of a sphere as it sinks through a viscous lluid. The 

 velocity of fall of colloidal particles in a ra])illary 

 tube, as the\ descended to take up their final distribu- 

 tion, was carefully observed and bv substitution in 

 Stoke's efjuation the mass of the particles calculated. 

 Everything is now rcad\' for the determination of 

 the Kinetic Theory constant. On the basis of this 

 theory, the constant has been worked out to be 

 7X10 *'. Judge of the interest and importance of 

 the above in\cstigation, absolutely experimental 

 throughout, when the value of the constant was 

 found to be 6-9x lO"'^'. Since then, more accurate 

 determinations have been made and it seems that 

 the above method comprises a means for the deter- 

 mination of that fundamental constant, the number 



of molecules per gram-molecule, which is cajjable of 

 almost unlimited |)recision. The gas-laws, already 

 api)lied by van't Hoff to dilute solutions, are thus 

 extended by Perrin to uniform emulsions. In 

 addition, his researches form no mean part of the 

 evidence which has lifted the "molecule" out of 

 hypothesis into reality. 



Enough has been said to indicate the wide scripe 

 of a[)plication of the ultramicroscope, and there is 

 everv reason to believe that this scope will be con- 

 siderably extended in the near future. Even now 

 we hear of such developments as the cinematograph- 

 ing of the particles visible by its aid, particularly 

 blood -corpuscles and attendant disease -germs. 

 Certainly it is to this apparatus that we look for 

 further information regarding the nature of proto- 

 plasm and the problem of living matter, it being 

 reserved for future reviewers to say whether or no 

 these expectations have been realised. 



CORRESPONDENCE. 



ON THE RI':SEMHLANCE OF THE FLORA AND 

 FAUNA OF HilCLAND TO THAT t)F THE SPANISH 

 PENINSULA. 

 To the Editors of '' Knowledge." 

 Sirs, — In the very interesting article by Dr. Scharff in the 

 March number of " Knowledge," he mentions that the beetle, 

 Rhopalomcsites tardsi, occurs only in the south-west of 

 England. It may perhaps interest some of your readers to 

 know that I have taken it in some numbers in the neighbourhood 

 of Hastings. It occurred in an old holly hedge which had 

 been cut back repeatedly, apparently for many years. This 

 hedge was perhaps twenty yards long, and the old stumps 

 were full of the burrows. I am under the impression that the 

 perfect insects occurred only in the branches which had been 

 topped two years before, but of this I am not sure. A row of 

 holly trees which had been allowed to grow unchecked a few 

 yards further on yielded no specimens, though carefully 

 searched. The same is true of many other holly hedges that 

 I searched in vain in the district. The specimens varied very 

 much in size, but the largest was less than half the size of 

 Irish specimens that I have seen. 



WM. WILLS ESAM, B.A. 



THE SPECTROSCOPIC ASPECT OF IMPACT 



THEORY. 



To the Editors of " Knowledge." 



Sirs, — I was very pleased with Mr. Raffetyfor his extremely 

 clear statements of the many difficulties in the way of a full 

 detailed interpretation of the spectra of novae. I wish also 

 to thank him for showing so clearly how remarkably the 

 theory of the third body explains all the generic peculiarities. 



There are so many chemical and physical agencies at work 

 that the spectrum lines of tbe first elements will hardly be 

 likely to show speeds corresponding to the law of Graham. 

 Immediately after the impact the molecular speeds will be all 

 alike ; hence we have to remember that the temperatures 

 given at collision by the conversion of inoler into molecular 

 motion is inversely as the atomic weights. These great 

 differences can only be partially equalised. We have also to 

 remember that is the first state of a third body, the light gases 

 are at the centre — exactly opposite to that of an ordinary star 

 — and that the centre must be enormously cooler than the 

 surface. 



The spindle form of the third body would have atomic 

 weights from one to ten at centre ; from ten to forty at outside 



and from forty to eighty at its ends. The escaping gases 

 from the centre will lower the temperature of the elements on 

 the outside, but not of the ends ; hence iron, titanian, and so 

 on, may actually show a higher velocity than sodium or 

 potassium, and, as the brilliant nucleus will not generally be 

 shining through the ends, the iron lines will show no reversal 

 on the edge towards the violet. .Ml the deductions have not 

 been able to be observed. Hut every portion and every 

 characteristic that can be observed correspond. The corres- 

 pondences are so numerous and so singular, so abnormal, as 

 absolutely to demonstrate the fact that Nova Persei was cer- 

 tainly a third star struck from grazing suns. It is satisfactory 

 to know that an astronomer of repute at the last meeting of 

 the Royal Astronomical Society said "that he thought that 

 Professor Bickerton's conclusions were sound and that the 

 very sudden flare-up of novae indicated the collision of two 

 tolerably condensed bodies." 



HvDE Park, W. A. W. BICKERTON. 



THE MECHANISM AND ISE ()V THE APOPHYSES 



OF THE SCALES OF THE CONKS OF THl". 



SCOTS PINE. 



To the Editors of " Knowledge." 



Sirs, — The thick tip of the apophyses is covered with 

 hardened resin, but the broad thick part below the tip consists 

 of spongy cork-cells with several vascular cords running 

 through it. The outer surface is striated, and water readily 

 penetrates it and saturates the spongy cork. 



The inner side of the scale tapering to the base consists of a 

 compact layer of thick-walled fibres with a wavy outline. 



If the apophyses only be kept in water they soon become 

 saturated; on the other hand, the fibrous layer will presumably 

 tend to contract by shortening the fibres. At all events, the 

 result is that the scales of a cone, in which they are widely 

 spread out. now all contract and the cone closes up tight. 



We thus see why, after fertilisation of the ovules, the 

 apophyses of the green scales, filled with sap, close up and 

 protect the developing ovules. .After .ill, the moisture has been 

 utilised for the ovules, presumably carried down by the 

 vascular cords penetrating the corky tissue of the apophyses. 

 Then the scales expand, being dried up. and the now ripe 

 seeds are liberated. When the cone finally falls to the 

 ground all the scales are spread out, but if the soil be wet the 

 apophyses re-absorb moisture, and the scales close up again. 



GEO. HENSLOW. 



