December 21, 1899] 



NATURE 



87 



attts), two Cape Bucephalus {Dispholidus typus), a Puff Adder 

 {Bitis arietans) from South Africa, presented by Mr. J. E. 

 Matcham ; a Common Rattlesnake {Crotalus durissus), two 

 Horrid Rattlesnakes {Crotalus horridus) from North America, 

 deposited ; four Common Sheldrakes ( Tadorita cornnta), two 

 White-fronted Geese {Anscr alhifrons), European, purchased ; 

 a Harnessed Antelope ( Tragelaphiis scripia, 9 ), a Brush-tailed 

 Kangaroo {Petrogale penicillata, i ), born in the Gardens. 



OUR ASTRONOMICAL COLUMN. 

 New Minor Planet (1899 E.Z.). — Circular No. 25 from the 

 Centralstelle at Kiel contains an ephemeris of the planet ob- 

 served by Mr. E. F. Coddington in October and November 

 last. Herr Kreutz thinks there seems no doubt that this is 

 identical with the planet found by Dr. J. Palisa (1896 CO.), and 

 the ephemeris is given with the possibility that more observa- 

 tions may definitely settle the point. 



Ephemeris for \ih. Berlin Mean Time. 

 DecL 



-4 59'o 

 4 36-4 

 4 I3'3 

 3 497 

 3 25-8 



-3 1-5 



OF THE " ASTRONOMISCHE 



Nachrichten." — We have received a card from Herr H. 

 Kreutz, of the Central Bureau at Kiel, respecting an important 

 alteration in the method of publishing the astronomical inform- 

 ation hitherto given in the Astronomischc Nachrichten, which is 

 one of the most important foreign journals dealing with current 

 astronomical observations. With the beginning of the New 

 Near the original publication will be confined to the recording 

 of general observations, while a separate paper will be issued to 

 contain the ephemerides of comets, planets, <S;c. The subscrip- 

 tion to the new pait will be 10 marks yearly. Arrangements 

 are being made for this addition at Kiel, Niemannsweg 103, 

 and subscriptions should be sent there direct. 



CoMi'ANiON TO the OBSERVATORY.— We have received the 

 Companion to the Observatory for the year 1900. In arrange- 

 ment this closely resembles those of previous years, giving most 

 of the more important data for the observation of celestial 

 ol)jects. Beginning with one page showing for every week the 

 time of rising and setting of the sun, its declination at noon, 

 mean and sidereal time, and the moon's phases, there follows a 

 calendar, giving for every day in the year the setting, southing, 

 declination of the moon and the longitude of its terminator. 

 -Mr. Denning again contributes his list of radiant points of 

 the principal meteor showers during the year. Then follow 

 useful particulars of the R.A., Decl., diameters, times of rising, 

 southing and setting of the planets, with the times of elongation, 

 opposition, conjunction, &c. Occultations, configurations of 

 the satellites of Jupiter, Saturn, Uranus and Neptune occupy 

 the next ten pages. Mr. Crommellin contributes an ephemeris of 

 Eros for the period about the opposition in December. The 

 rest of the book is occupied with an ephemeris for physical obser- 

 vations of the sun, and the mean places and times of maxima and 

 minima, of the more noticeable variable stars. 



RECENT RESEARCHES ON URIC ACID. 



' PHE uninterrupted stream of new researches which has 

 •*■ issued from the laboratory of Prof. Emil Fischer at 

 Berlin since 1895 threatens to bewilder even the careful 

 student of chemistry or physiology. The following brief 

 summary of the results may be found useful. 



Uric acid is an excretory or waste product of animal life, and 

 is closely related chemically to many substances such as 

 paraxanthine and heteroxanthine, which are associated with it 

 in urine ; xanthine, adenine, and guanine, which probably form 

 part of the nucleins of cells, and theobromine, theophylline and 

 caffeine, the physiologically active constituents of tea, coffee 

 and cocoa. 



An accurate knowledge of the constitution of these sub- 

 stances is therefore of the first importance to physiologists, 

 whilst a satisfactory process for utilising uric acid— which is a 



NO. 1573, VOL. 61] 



plentiful constituent of guano— in the synthe.sis of theobromine 

 or caffeine would possess coi>siderable therapeutic interest as 

 well as commercial value. The many difiticulties encountered 

 by Prof. Fischer in the solution of these problems have been 

 met with his accustomed skill and resource, which are the 

 admiration and despair of the present-day chemist, and we are 

 now not only in possession of a clear and complete knowledge 

 of the relationship which exists betwefcn these complex products 

 of animal and plant life, but we may anticipate before long 

 their appearance as commercial products. 



Fischer has shown that in all these compounds the same 

 atomic framework is present and may be represented as follows, 

 the relative position of the atoms being denoted by the 

 numbers i to 9. 



I 6 



N C 



If the four additional hydrogen atoms necessary to satisfy 

 the valencies of the carbon and nitrogen atoms be now added, 

 the structure of the mother substance of the whole series is 

 obtained, a compound which has been actually prepared by 

 Fischer, and named purine (purum uriciim). 

 N=CH 

 I I 

 HC C— NH 



^CH 



N-C— N 



Purine. 



Hypoxanthine, xanthine and uric acid may be derived from 

 purine by the addition of one, two and three oxygen atoms. 



HN 



I I 

 HC C 



CO 



-NH 



HN- 



I 

 OC 



-CO 



i 

 c- 



CH 



NH 



>CH 



HN^ 



I 



-CO 



. I 

 OC C— NH 



>CO 



N— C— N HN— C— N HN— C— NH 



Hypoxanthine Xanthine Uric acid 



(6-oxypurine). (2 : 6-dioxypurine). (2:6: 8-trioxypurine). 



Adenine is purine in which the hydrogen atom in position 6 

 is replaced by an amido-group, whilst guanine is hypoxanthine 

 with an amido-group in position 2. 



N = C.NH2 HN— CO 



II II 



HC C— NH HoNC C— NH 



>CH 



^CH 



-N 



N— C— N N— C- 



Adenine. Guanine. 



Heteroxanthine, theophylline, paraxanthine, theobromine 

 and caffeine are respectively mono-, di- and tri-melhyl xan- 

 thines. 



HN— CO (CH3)N— CO 



I I 

 CO C— N(CH3) 



I II > 



HN— C-7-N 



Paraxanthine 



(i :7-dimethyl xanthine). 



I I 



CO C— N(CH3) 



I II >" 



HN— C— N 



Heteroxanthine 

 (7-methyl xanthine). 



{CH3)N— CO 



I I 



CO C— NH 



I i| >" 

 (CH,)N— C— N 



Theophylline 

 (i :3-dimethyl xanthine.) 



HN-CO (CH3)N-CO 



II II 



CO C— N(CH3) CO C-N(CH,) 



I ii >CH I II >CH 



(CH3)N-C— N 



Theobromine 

 (3 : 7-dimethyl xanthine). 



(CH3)N-C-N 



(Caffeine 

 (1:3: 7-trimethyl xanthine). 



