CORRESPONDENCE, 



The Art of Cataloguing. 

 Sir, — Whoever reviewed Mr. Seward's Catalogue of the Mesozoic Plants in the 

 British Museum in your August number (p. 147) is no doubt a competent botanist, 

 but can know very little about museum work. In cataloguing a series of fossils, 

 whether plants or animals, " a bare quotation of the register numbers," would by 

 no means serve the purpose, though your reviewer seems to think it would. In the 

 first place, register numbers have an unfortunate habit of coming off, and it is 

 exceedingly useful to have some subsidiary means of identifying the specimens. 

 Secondly, a register number alone conveys no information to a worker at a distance ; 

 and it is surely advisable that such an one should be informed whether a specimen 

 is a mere fragment, or shows some structural features, so that when he comes to 

 the Museum he may be able to say at once exactly which specimens he wishes to 

 see. At the worst, the system adopted by Mr. Seward, as by some other cataloguers 

 before him, can do nothing more terrible than take up the space of which your 

 reviewer seems so jealous ; and I venture to submit that the space is by no means 

 wasted. 



Geological Department, F. A. Bather. 



British Museum. 



Nascent Elements. 



With regard to the question of nascent elements, has it been considered 

 whether the conditions which apply to several gases in the above state also apply 

 to them when solid, i.e., if hydrogen could be evolved under conditions consistent 

 with a solid state, what peculiarities different to solid hydrogen, evolved and then 

 solidified, would it exhibit ? Also when, say, carbon is freed from a compound 

 does it exhibit any nascent phenomena ? 



Would not a solution of this problem shed light on the supposed action of 

 chlorophyll in the formation of starch from COo and H.^O in plants ? 



Hoping you will discuss this question in your valuable magazine. 



Jno. E. Hardman. 

 78 Chorley Old Road, Bolton. E. P. Greenhalgh. 



[Whatever may be the conditions requisite for the evolution of solid hydrogen, 

 those existing in the leaves of living green plants must be so vastly different as to 

 render comparison useless. As regards carbon, it is extremely improbable that the 

 free element enters at all into the process of formation of organic matter from 

 carbon di-oxide and water ; it is generally supposed that the COo loses only half 

 of its oxygen, the remaining group (CO) combining with the hydrogen of the water 

 to form a compound containing the three elements in these proportions (CHoO). 

 This compound is a much simpler one than starch, which is only deposited by the 

 protoplasm when the amount of carbohydrate material present in the cell is in 

 excess of that needed for the immediate use of the plant. — Editor.] 



Natural Selection. 



In answer to Professor Henslow and " Entomophilos," I may perhaps state 



that the various facts on which my statements were based are contained in my own 



and other papers, to which I must refer them. The word "apparently" in the 



phrase they object to might be replaced perhaps by " possibly " or " probably." 



