Jan. 8, 1885] 



NA JURE 



217 



course would destroy and obliterate these delicate forms. There 

 must be a steady set of wind, enough and not too much of it, 

 and the air must be saturated with moisture in a certain state of 

 molecular division. Some of these data might, perhaps, with 

 the resources of a modern laboratory, be settled by experiment. 

 If the experiment succeeded it would be an extremely pretty 

 one. F. Pollock 



C. C. Collier 

 Woodtown, Harabridge, South Devon, January 2 



Krukenberg's Chromatological Speculations 

 My attention has been lately called to a recent publication of 

 Dr. C. F. W. Krukenberg, entitled " Grundziige einer Ver- 

 gleichenden Physiologic der Farbstoffe und der Farben," in which 

 some remarks and misstatements occur relative to my work, 

 which in self-defence I feel I am not justified in letting pass 

 without comment. 1 



(1) With regard to his observations on the colouring matter 

 obtained by me from the integument of certain invertebrates, 

 and which I called " dermochrome," I do not see why I should 

 have left it unpublished because three-quarters of a year before 

 he had found that " lipochromes " were widely distributed in the 

 animal kingdom. I found that lutein and hoematoporphyrin 

 occurred together in a peculiar combination, and said so. I 

 suppose the offence lies in the name " lutein." This word must 

 now, according to Krukenberg, be got rid of, because he has 

 chosen to call it " lipochrome." Perhaps, after all, "lutein" 

 is more appropriate, as it does not mean fat pigment ; for this 

 pigment occurs where there is no fat, e.g. it is not derived from 

 fat in the Corpora littea. Krukenberg bases his conclusions 

 mainly on the reactions of the solid pigment with nitric and 

 sulphuric acid and iodine, but I hope to have something to say 

 on this point before long. 



(2) Krukenberg maintains that the chlorophyll of cantharides 

 is due to that in the intestines of these beetles. He committed 

 himself to this theory at an early stage of his investigations, 

 before he knew of Pocklingions observations ; but after seeing the 

 abstract of my paper read at the meeting of the British Associa- 

 tion at Southport in 1883, in which I called attention to Pock- 

 lington's work, he makes it appear that he knew all about it 

 long ago, which is not fair. Now since Pocklington and I 

 obtained chlorophyll from the elytra of these beetles, I do not 

 think the above theory can be accepted, except it can be proved 

 by Krukenberg that the intestine ramifies through the elytra. 



(3) Krukenberg says that / "assume" that the chlorophyll 

 spectrum seen by me in the integument of the larva of Pieris 

 rapa is due to chlorophyll in that situation, whereas it is really 

 due to chlorophyll-holding masses in the intestine. I never did 

 " assume " anything of the sort. I said distinctly at Southport 

 that it was due to food chlorophyll in the intestine, as could 

 easily be proved, for on emptying the intestine the chlorophyll 

 band could no longer be seen. This must be a wilful misrepre- 

 sentation, as he acquired the knowledge of Pocklington's work 

 from the same abstract in which my explanation occurs. 



(4) He further says that my knowledge of the literature of the 

 subject must be great when I assume that he has confused 

 " anthea green " and " diatom yellow," whereas I said distinctly 

 " it would appear, according to Geddes " (see Geddes' paper in 

 Nature, vol. xxv. p. 303) that he had confused them. I 

 may, however, now observe that his supposition that the colour- 

 ing matter of the yellow cells of Anthea is what he calls a 

 " hepatochromate " can easily be disproved ; all that is necessary 

 is to add a little caustic potash or caustic soda to its alcoholic 

 solution when the colouring matter becomes completely altered ; 

 for this reason anydeductions drawn from Krukenberg's "saponi- 

 fication method " in this case are of little value. 



(5) Krukenberg says he had found "chlorophyll-like stuffs" 

 in the livers of animals before I had done so. I am sure this 

 statement is open to question, as his spectra are not accurate re- 

 presentations of what is seen in solutions of enterochlorophyll. 

 In most cases only one or two bands are shown by him, and the 

 other proofs brought forward by me are not given in the accom- 

 panying text. If his own test for a true chlorophyll be accepted, 

 I can, and hope shortly to, show that animal chlorophyll is a 

 true chlorophyll, and can be obtained in the crystallised state, 



The papers in which my observations on the subjects referred to were 

 published are:— Proc. Roy. Sec, 1883 (No. 226); Proc. Birmingham 

 Philos.Soc., vol. Hi., 1883; and Brit. Assuc. Reports. 



and the crystals are the same as those obtained by Dr. Hansen, 

 an abstract of who«e work will be found in this journal (vol. xxx. 

 p. 224). 



(6) It is further suggested that the darkening of the bands in 

 solutions of " echinochrome" (a pigment whose spectrum I have 

 lately described) produced by adding sulphide of ammonium, is 

 caused by precipitation of certain ingredients. This is not 

 the case. The same appearance is produced by stannous chloride 

 and other reducing agents. I have, however, lately succeeded 

 in isolating this pigment, and can confirm my former results. I 

 hope to publish shortly an account of the spectra of its solutions. 



(7) Krukenberg makes it appear that I have said that the green 

 gland of the crayfish contains hemoglobin. I never said so. 

 The statement was this : " In the green gland of one crayfish a 

 band was detected which, I think, was due to reduced fiu matin, 

 but it was absent in the second specimen examined." Perhaps 

 Krukenberg thinks that haemoglobin and hrematin are the same. 



(8) I am made responsible for the statement that the eye of 

 the house-fly contains haemoglobin ; I never said so, nor can I 

 agree with Krukenberg that it gives no band. It gives a band 

 at D, and is not similar to the pigment of the eye of Cephalopods, 

 which he assumes to be the case. 



I leave the inferences to be deduced from the above statements 

 to others ; but I must protest against Krukenberg's treatment of 

 my work. It is at least satisfactory to know that my experience 

 is not unique, as other English, German, French, and Italian 

 workers receive an equally fair treatment by Dr. Krukenberg. 



Wolverhampton, Dec. 23, 1884 C. A. MacMunn 



Our Future Clocks and Watches 

 I would suggest, as a modification of " R. B.'s" suggestion- 

 in Nature (p. 80), that the striking of the clocks on the 

 twenty-four system might be varied at each quarter of the day, 

 so as to indicate the time without so much striking. Thus, 

 1 (a.m.) to 6 might be indicated by the usual method ; 7 could 

 be indicated by two strokes, a pause, and one stroke ; 8, by two 

 strokes, a pause, and two strokes; and so on to 12 ; 13, by 

 three strokes, a pause, and one stroke ; and so on to 18 ; 19, 

 by four strokes, a pause, and one stroke ; and so on to 24, 

 which being thus indicated by only ten strokes would require 

 less effort to c Hint, and make less noise than by the old system. 

 Dials might be modified in the same way. Instead of twelve there 

 would be only six divisions around the dial, and the quarter of the 

 day could be indicated by a small wheel revolving behind a peep- 

 hole, or by a third hand (which could be very short) revolving 

 once a day over four divisions or quadrants, marked on the 

 dial near the axis. People, however, would seldom or never 

 need to look at this. Thus would be done away all the objec 

 tions urged by Harmer. The hour-markings are only conven- 

 tional signs any way, and it does not make any especial differ- 

 ence in what way the hours are indicated if people would only 

 accustom themselves to the use of the twenty-four hour system 

 in speaking and writing. H. H. Clayton 



Ann Arbor, Michigan, December 20, 1884 



MODE OF RECKONING TIME AMONGST 

 VARIOUS PEOPLES 

 H""* H E recent Prime Meridian Conference at Washington 

 -*• has attracted attention to the methods employed at 

 various periods, and amongst peoples in different stages 

 of civilisation, to reckon time. Dr. Robert Schram, on 

 October 24, read an interesting paper on this subject 

 before the Geographical Society of Vienna, in which he 

 dealt chiefly with the Chinese, Hindoos, and the jews. 

 The three units of measurement given by Nature herself 

 are the rotation of the earth on its own axis, the revolution 

 of the moon in its orbit, and that of the earth around the 

 sun : these are wholly independent of each other, and 

 neither is an aliquot part of the others. But from the 

 earliest times efforts have been made to connect these 

 units ; there is the attempt to balance all three, which 

 gives the luni-solar year, or those to connect the day with 

 the course of the sun or of the moon, from which we get 

 the solar or lunar year. In the earliest times the 

 most 1 (implicated of these, the luni-solar year, in which it 



