June 1, 1000.] 



KNOWLEDGE, 



141 



differ in many ways from those in the terrestrial spec- 

 trum. Lookyer has found that on certain days cei-tain lines 

 are absent; on other days other lines ; and so on in almost 

 endless variety. The lines of a sun-spot are different 

 from those of a prominence. Some of the iron lines 

 may be bent, indicating rapid motion of the luminous 

 material, while other lines in the same spectrum remain 

 straight, indicating comparative rest. The lines indi- 

 cating motion vary from place to place and from dr.y 

 to day. The set of bent lines in a sun-spot is different 

 from the set of bent lines in a prominence. In short, 

 an indivisible atom can move and remain at rest at one 

 and the same time I The only feasible explanation of 

 these facts seems to be that the iron has been dissociated 

 by heat, and that the constituents have been pai'tly 

 separated. 



The idea that each substance ha.s a spectrum entirely 

 and specially its own is untrue. Many lines of different 

 metals coincide. Thus out of sixty-two lines of iron in 

 the region 39 to 40, no less than forty-four coincided 

 with lines of other metals. 



It has also been shown that many elements have 

 fluted as well as line spectra. The former are 

 characteristic of low temperatures. As the temperature 

 rises, the lines appear one bv one. The series of spectra 

 so obtained is exactly pai-allel in appearance with the 

 series obtained when a known compound is dissociated 

 bv heat. There is a gradual thinning-out of bands and 

 appearing of lines. 



The witness of the stars to elementai-y evolution is 

 much more striking and direct. Lockyer, long agj, 

 pointed out in a general way that the hottest stars have 

 the simplest chemical composition, and he has I'ecently 

 developed this subject much more fully. In a lecoure 

 .deliver&i in the spring of last year he said: — "Disso- 

 ciation reveals to us the forms the coming together of 

 which has produced the thing dissociated or broken up 

 by heat. If this be so. the final products of di.ssociation 

 or breaking up by heat must be the earliest chemical 

 forms. Hence we must regard the chemical substances 

 which visibly exist alone in the hottest stars as repre- 

 senting the ear-liest evolutionary forms.' 



The lecturer then gave details concerning the increase 

 of chemical complexity in stars with decrease of tem- 

 perature : — "We find that in the hottest stars we get 

 a very small number of chemical elements ; as we come 

 down from the hottest star to the cooler ones the number 

 of spectral lines increases, and with the number of lines 

 of course the number of chemical elements. In the 

 hottest stars of all, we deal with a form of hydrogen 

 which we do not know anything about here (but which 

 we suppose to be due to the presence of a very hif;li 

 temperature), hydrogen as we know it, the cleveite g..ses, 

 and magnesium and calcium in forms which are difficult 

 to get here ; we think we get them by using the highest 

 temperatures available in our laboratories. In the stars 

 of the next lower temperature we find the existence of 

 these things continued in addition to the introduction 

 of oxygen, nitrogen and carlx)n. In the next cooler 

 stars we get silicon added; in the next we get the 

 forms of iron, titanium, copper, and manganese, which 

 we can produce at the very highest temperatures in our 

 laboratories; and it is only when we como to stars much 

 cooler that we find the ordinai-y indications of iron, 

 calciiim and manganese and other metals. All these, 

 therefore, seem to be forms produced by the running 

 down of temperature. As certain new forms are intro- 

 cuced at each stage, so certain old forms disappear." 



This chain of facts, thus briefly stated, confirms in a 

 most striking way tho chemical speculation that has been 

 going on more or less continuously since tho time of 

 Prout ; and gives solid support to the theory of the 

 evolution of the elements. Tho only mistake that Prout 

 made — a very natural mistake at the time — was in 

 taking hydrogen as his starting point. For if evolution 

 of the elements has really taken place, some modification 

 of Prout's hypothesis must bo true. The atomic weights 

 of the elements must bo multiples of that fraction of hy- 

 drogen which may residt from tho di.ssociation of hy- 

 drogen. The fact that the verification of this is beyond 

 the reach of analytical chemistry is beside tho question ; 

 but it is worth noting that some of the most accurate 

 atomic weight determinations ever made were due to 

 tho controversy over Prout's hypothesis, which has, in 

 this way, at least, borne practical fruit. 



It has long ago been noticed that the essential ele- 

 ments of living matter are all of relatively low atomic 

 weight. Sir Norman Lockyer has also pointed out tho 

 interesting fact that these elements are precisely those 

 found in the hottest stars. In other words, organic 

 evolution began among the earliest and simplest chemical 

 forms ; and the mai-vellous mobility and plasticity of 

 the protoplasmic cell are due to its being formed from 

 the simplest, and, presumably, the most mobile and most 

 plastic of the elements. We have hero " a quite new 

 bond between man and the st,ars." 



Before biological evolution could begin, there was a 

 chemical evolution like it in many respects, chai-acterised 

 by the same progi-ess from simplicity to complexity, bv 

 the appearance of new forms and the disappearance of 

 old ones. As tho rocks are divided into strata according 

 to the fossils they contain, so the stars can be divided 

 into " strata " according to their chemical composition 

 and the period of evolution they have reached. 



This chemical evolution comes very exactly under ih*j 

 philosophical definition of evolution in general. It is a 

 progress from " an indefinite, incoherent homogeneity 

 to a definite, coherent heterogeneity." 



i*ticvoscopi>. 



By John H. Cooke, p.l.s., f.g.s. 



The residua and strainintjs obtained from ordinary tap water 

 will provide the microsoopist with an abundance of matori,-d for 

 examination. Among the organisms that he will ])robablv meet 

 with ai'e the fat little rotifer, Triai-ihra hriKjiseta, hobbling 

 along on his long delicate stilts in company with the pretty 

 little long-spined Aiiureii. hm(//.i2>'>ui. The Vortieellida; and 

 Entomostraca are often in great force, with diatoms and 

 desmids i nnumerable. Diiiuhri/nn xerhilmia, a curious compound 

 flagellate organism, like animated ears of barley, though not so 

 numerous, are invariably present in greater or lessor nnmliers. 

 A b.ag made of several thicknesses of very fine nnislin and tied 

 on the water tap, so that tho water strains gently tlirougb it, is 

 a rough and ready, but, on the whole, a satisfactciry way of 

 capturing them. 



A practical way for obtaining crystals from dog's blood is 

 suggested by Dr. S. Waterman. Oolibrinate and mix water in 

 e<iual parts to each volume of blood. Add to four volumes of 

 the blood .solution one vohime of alcohol. Set the mixture to 

 rest for twenty-four hours at a terai)erature of C^ or less. 

 The crystals formed arc filtered off, pressed, dissolved in the 

 smallest c|uantity of water, say '25 to .^d |)er cent., exposed to a 

 temperature of 10", and left umlisturbed for twcnty-fourhours. 

 The whole solution will be found converted into a crystallised 

 mass. 



The production of lutmoglobin crystals is surrounded at times 

 with more or less difficulty, owing to the rapidity with which 



