January i8, 1900] 



NA TURE 



273 



some trial radiant-points for any remarkable shooting-stars or 

 large meteors of the two past years' expected maximum Bielid 

 periods which may have been recorded. 



Observatory House, Slough, A. S. Herschei.. 



December l6th, 1899. 



Is New Zealand a Zoological Region? 



Wii,i. you allow me to mak€ one remark on the letter of Mr. 

 11. Farquhar (p. 246), advocating an affirmative answer to the 

 above question. It is this : Throughout the whole argument 

 there is an assumption which vitiates it, namely, that the amount 

 of resemblance of the New Zealand fauna to that of Australia 

 is what alone determines its resemblance to that of the 

 Australian Region. 



Apparently, Mr. Farquhar does not believe that New 

 c aledonia and the New Hebrides belong to the Australian 

 Region, otherwise he would not adduce the fact of the land- 

 sliells of New Zealand being related to those of the above- 

 named islands as an argument in his favour ; and if these are 

 mitted, then must New Guinea be also omitted. And if 

 \ustralia by itself is to become a "Zoological Region," New 

 I .uinea and its surrounding islands must be also a " Region," 

 the Central Pacific Islands another, and the Sandwich Islands 

 yet another ! This indicates the difficulties that arise if the 

 Australian Region, as originally defined by Dr. Sclater and 

 myself— and which I still hold to be far more natural than any 

 subdivision can make it — be rejected. 



Alfred R. Wallace. 



I 



Molecular Structure of Organised Bodies, 



Prof. Vines, in his " Physiology of Plants," says that the 

 molecular structure of cells can only be inferred from their pro- 

 perties, and that a correct conception of this structure is essen- 

 tial for a proper comprehension of cell growth. In the same work 

 the author also states that Naegeli argues : " Since the optical 

 properties of these organised structures are apparently not de- 

 pendent, like those of a crystal or a piece of glass, upon the 

 relative position of their constituent particles, they must be in- 

 herent in the particles themselves. Each micellae, then, possess 

 the optical poperties of anisotropic crystals. Naegeli concluded, 

 therefore, that the micellre are crystals." 



Naegeli's micellae theory rests almost entirely on the failure 

 of any effort to temporarily destroy the anisotropism of organised 

 structure. Obviously, if it were possible to so act on or swell 

 a vegetable fibre that its anisotropism were destroyed, and that 

 this anisotropism returned after the treatment were discontinued, 

 -Naegeli's theory, as far as it relates to the optical properties of 

 micellae, would fall to the ground. 



It is well known that organised structures cease to be doubly 

 refractive at the moment when their organised structure is de- 

 stroyed. This is usually explained by saying the micellae are at 

 the same time disintegrated. 



As far as I am aware, it has never been shown that this 

 property of double refraction, common to organised structures, 

 can be destroyed by suitable swelling, and restored again when 

 the body returns to its original condition. I have been able to 

 do this, in the case of cotton fibre, and it seems to me to give 

 the coup de grace to Naegeli's theory. 



I take it that if in one instance the anisotropism of organised 

 structure can be temporarily destroyed, it is a correct inference, 

 lliat to do so in every case only requires a suitable medium ; 

 which will reduce the strains to a necessary degree without the 

 destruction of the physical form of the organised structure. 



In the course of some investigations on the destruction of 

 nitro cellulose fibres, by means of solvents, I observed that in 

 one particular case the double refraction disappeared long before 

 the physical structure, and that on getting rid of, or diluting the 

 solvent, the anisotropism returned. It is because I think this 

 nljservation will be of interest to biologists I am troubling you 

 <! length. 



It is well known that on converting fibrous cellulose into nitro- 



■llulose, the fibres retain their optical properties as regards 



polarised light. Nitrocellulose, however, has a very wide range 



of solvents, and the examination of organised fibres when treated 



with solvent, becomes very e.^tended. 



Most nitro-cellulose solvents, such as acetone, nitro-benzene, 

 :ie ethers, &c., do not lessen the anisotropic properties. The 

 iires may he swollen to twice their diameter, but still polarise 



NO. 1577, VOL. 61] 



light, until their physical structure is quite gone. This is not so, 

 however, if nitro-cellulose fibres are acted upon with a mixture 

 of acetone, benzene and ethyl alcohol. With this solvent the nitro- 

 cellulose becomes gelatinised, and the anisotropism disappears, 

 yet on examination the fibres are seen to be present in great 

 abundance. These isotropic fibres can be given their double 

 refractive properties again, by diluting the solvent with excess 

 of alcohol or benzene. 



The accompanying photographs show this action very well. 



Nitro-cellulose was prepared from cotton-wool, with large 

 excess of acids, so that there should be no unnitrated fibres 

 present. The resulting nitro-cellulose was practically all of the 



Fig. I. 



insoluble variety, and contained 1 3 '3 percent, nitrogen. It wa 

 completely soluble in excess of acetone, and contained no cotton 

 fibres. 



Some of this nitro-cellulose was treated with ten times its 

 weight of a solvent consisting of: 



6 parts benzene 



3 „ alcohol 



2 ,, acetone 

 and allowed to stand in a stoppered bottle twenty-four hours, a 

 jelly resulted. 



Figs. I., II. and III. are from a little of this jelly, mounted 

 with two crossed cotton fibres to fix the point of view, and give 

 an object to focus and develop. The three photographs are 

 taken from the same slide and the same point of view. 



Fig. I. is a view under crossed nicols of the jelly, and taken 

 immediately after mounting. It will be noticed that the object 

 shifted slightly during exposure. 



