228 



NA TURE 



{Jan. 2 2, 1874 



T^ 



ON THE STUDY OF NATURAL HISTORY* 



'HE value of Natural History would be more fully ap- 

 preciated if its higher aims were more perfectly undt r- 

 stood. Too many fancied that the study of natural 

 history consisted in mere collecting and naming, and 

 looking at pretty objects. This was, however, mere 

 scientific play ; whereas the more thorough study was 

 real work, of use not only ns an intellectual training, but 

 also as applied to the practical life of every day. They 

 often heard the remark that the proper study of mankind 

 was man, but to confine their study to him would be to 

 take the first term of a great series, and neglect all the 

 other terms — a proceeding which could lead only to 

 an inaccurate and one-sided view of the order of the 

 universe. 



As an illustration of the connection of one class of facts 

 with another he would briefly describe some of the re- 

 sults to which he had been recently led by applying 

 physical methods to the study of the evolution of 

 plants. He had studied the changes that had occurred 

 in the colouring matters in the leaves and flowers 

 during their development from a nrdimentary to a per- 

 fect state, and the connection between them and the 

 action of light, and had found that there was ap- 

 parently a most remarkable correlation. When more 

 and more developed under the influence of light, 

 coloured compounds were formed which are more and 

 more easily decomposed by the action of light and air 

 when they were no longer parts of living plants, but dis- 

 solved out from them. There was thus apparently some 

 condition in living plants which actually reversed these 

 reactions. 



He had also found that in the more rudimentary 

 state of the leaves of the highest classes the colour- 

 ing matters corresponded with those found in lower 

 classes, and in the case of the petals of flowers 

 their more rudimentary condition often corresponded 

 with some other variety, which thus appeared as if due 

 to a naturally arrested development of a particular kind. 

 This principle would perhaps serve to explain the greater 

 prevalence of flowers of particular coloui's in tropical or 

 colder regions and at different elevations. Now, since 

 the effect of the various rays of light was different, it 

 became a question of much interest to decide whether an 

 alteration in the character of the light of the sun would 

 produce a somewhat different effect in the case of other 

 classes of plants in which the fundamental colouring 

 matter diflered ; for example, whether light, with a rela- 

 tively greater amount of the blue rays, might not be 

 relatively more favourable to the cryptogamia than to the 

 flovi'ering plants. So far this was a mere theoretical 

 deduction ; but, if proved to be true by experiment, it 

 might, at all events, assist in explaining the difference in 

 the character of the vegetation of our globe at an earlier 

 epoch, when perhaps our sun was in a somewhat difl'e- 

 rent physical state, and the light more similar to that 

 of Sirius and other stars of the highest and bluer 

 type. 



The practical applications of natural history were of 

 course most varied, but he would now merely refer to such 

 as depended upon the equilibrium between different plants 

 and animals. The successful cultivation of useful plants 

 in a foreign country might depend upon very comphcated 

 conditions to be learned only by accurate study. The 

 accidental introduction of some plants or animals might 

 prove most injurious if there were no native check to 

 their inordinate multiplication. This was perhaps why in 

 some cases such importations were far more injurious 

 than in their native country, and it became of great 

 importance to learn what means could be taken to pro- 

 vide some adequate check. 



* From an address by Mr. H. C. Sorby at the annual convcrsazioiu of 

 the Sheffield Field Nalur.ilists' Club, Januarj- 5. 



TRILOBITES 

 TOACHIM BARRAUDE has published a preliminary 

 J epitome (Prague and Paris, 1871, 8vo) of an in- 

 tended supplement to his " Systfeme Silurien du Centre 

 de la Boheme." 



He therein gives a list of the fossils as yet found in 

 the Cambrian formation : — " PLANTyE ; Palasophycus, i 

 species ; Fucoides, 2 ; Archffiorrhiza, l ; Halcjioa, 2 ; 

 Cordaites, I ; Eophyton, 2 ; Froena, I ; Buthotrephis, i ; 

 Scotolithus, I ; Oldhamia, 3 ; PETRI FICATA INCERT.1E 

 Sedis ; Cruziana, 3 ; Lithodictyon, i ; Animalia : Ves- 

 tigia, vel Vermiinii, vel Crustaceorum, vel Molluscorum : 

 Psammichnites, 4 ; Spoigia : Astylospongia, I ; Calen- 

 tcrata : Protolycllia, i ; Ecliinodirmata : Spatangopsis, 

 I ; (doubtful Echinoderm ?), Agelacrinus, i ; Vi'?-/iies : Mi- 

 cropium, i ; Spirocolex, 2 ; Scolithus, 4 ; Monocraterion, 

 I ; Diplocraterion (Arenicolites), 4 ; Histioderma, i ; 

 Mollusca : Dictyonema, i ; Lingula, 2 ; Lingulella, i ; 

 Discina, I ; Obolus, I ; Hyolithus, i." 



Whilst this formation has only yielded 28 animals, his 

 next epoch, his " Silurische Primordial Fauna " supplies 

 366 species as follows : — 



The author remarks on the discordance between the 

 picture thus offered and that which should appear to give 

 any positive confirmation to Darwinism. He then goes 

 on to remark on some phenomena in the development of 

 Trilobites. 



According to the Darwinian theory, the development of 

 the individual should bear relation to the past develop- 

 ment of the species. Now Trilobites, as they devclopc, 

 increase in number of their body segments, and therefore 

 the earliest Trilobites ought to have few such segments. 

 But those of the primordial fauna are generally charac- 

 terised by the opposite condition, while the number is left 

 in those of the succeeding fauna. 



Again, on the Darwinian theory, there ought at first to 

 be but few types, the number increasing later. But, in 

 fact, out of seventy-five genera of Trilobites, no less than 

 seventy-two appear in the first two Silurian faunas, and 

 the three others at the beginning of the third fauna. More- 

 over, the perfection of organisation by no means gradually 

 increases but is quite irregular. 



Once more as regards orders, there is no approximation 

 as we recede in time. The Trilobites, PhyUopoda, and 

 Ostracoda, are as sharply differentiated at their very first 

 appearance as they are later, and the Trilobites of the 

 lowest beds are not less easy to divide into genera than 

 those of a later period. Boheinilla might, perhaps, be 



