May 5, 1921] 



Mtt/RE 



301 



Amongst the indispensable tables should be included 

 Zech's addition and subtraction log table, which is 

 easy to use and accurate. For eight-figure work the 

 best, if not the only, tables are Bauschinger's and 

 Peters 's. R. T. A. I. 



Johannesburg, April 4. 



The Colour of Primrose Flowers. 



Nature of April i, 1920, p. 139, published an 

 interesting article on the colouring matters of plants. 

 From this article it would appear that the normal 

 pale yellow colour of the primrose is due to a yellow 

 sap pigment, a derivative of flavone. Primroses, how- 

 ever, are found with a range in colour from deep 

 red to almost white. Can any of your readers say to 

 what this variation from the normal is due, and 

 whether the colours are anthocyans? 



Much attention has recently been directed in the 

 local Press to this variation in colour, and many 

 attempts made to account for it. It is common in 

 parts of Pembrokeshire, but is usually confined to a 

 particular bank or field in the district. 



It is said to occur only in the Coal Measures, and 

 is probably due to the presence of iron in the soil 

 or to insect action causing a cross with polyanthus. 

 It is even stated that to plant a normal primrose 

 upside down causes a red coloration. 



A possible theory may be the cross from poly- 

 anthus, but it is generally agreed that but one insect 

 affects primroses, called sometimes a " primrose 

 sprite," resembling a bumble-bee, but with a long, 

 characteristic proboscis. The late Lord Avebury in 

 "British Flowering Plants" suggests a moth. 



These variations are, however, found remote 

 from cultivation, and . I have not been able to 

 ascertain a single instance of a red primrose in a 

 cultivated garden unless planted there from a hedge- 

 bank, when it attains an even deeper red, and often 

 develops the umbel of the polyanthus. 



R. O. Latham. 



Pembrokeshire, .April 12. 



In reply to Major Latham's inquiry, I may say 

 that in the red primroses which I have examined the 

 colour is undoubtedly due to an anthocyan pigment. 

 Pale yellow or white primroses contain no anthocyan. 

 Flavonols rarely give rise to much colour, and do so 

 only when present as salts (phenolates) of metals. 

 Even in primroses there is often a very small amount 

 of a yellow plastid pigment present which produces pro- 

 portionately far greater colour effect than the flavonol 

 derivatives that exist in the sap. The conversion of 

 the yellow sap pigments (flavonols) to anthocyans is 

 a process of reduction. Exactly what causes such a 

 change to take place in plant-life is not yet fully 

 determined, but the work of Prof. Keeble and of Miss 

 Wheldale has done much towards elucidating this 

 matter. When, as I boy, I tried the method of plant- 

 ing primroses upside down to get red or variegated 

 varieties (the countrv folk in the district believed that 

 this method was effective), it was never a success. 

 In general, it would appear that new colour varieties 

 in flowers are most frequently produced as a result 

 of crossing. Seeds of red or white varieties of prim- 

 rose are offered bv some seedsmen. 



The Writer of the Article. 



The Resonance Theory of Hearing. 



In the absence of a reply to Dr. Hartridge (Nature, 

 April 14, p. 204) from a more authoritative quarter, 

 I venture to suggest that his expression " a con- 



NO. 2688, VOL. 107] 



tinuous musical note " is not appropriate to the 

 phenomenon discussed. By changing the t^me- 

 interval between successive siren-puffs from r to fr, 

 the experimenter interrupts the periodicity of the 

 vibrations producing the fundamental tone of his 

 note, and the consequent discontinuity in the note is 

 perceived by his ear as something indistinguishable 

 from a beat (which, physically, it is not). According 

 to the "dead beat " view, this effect in the sensorium 

 is due to the last vibration of the interrupted series, 

 because there is no resonator in the cochlea which 

 by continuing to vibrate would make the temporary 

 interruption imperceptible. If the interruption-effect 

 were lacking when the resumed vibrations are not of 

 precisely opposite phase, there would be something 

 in Dr. Hartridge 's argument. 



Though at present reluctant to contribute further 

 to what Prof. McKendrick has called an interminable 

 discussion, I hope that the Uoretgraphe which Mr. 

 Daniel Jones is shortly to install in the phonetics 

 laboratory in this college will bring a termination 

 within view. W. Perrett. 



L^niversity College, Gower Street, 

 London, W.C.i, April 28. 



Biological Terminology. 



I DO not wish to be drawn into the whirlwind of 

 controversy raised by Sir Archdall Reid; only from 

 a respectful distance would I protest against his obiter 

 dictum that "systematic zoology and botany are purely 

 descriptive" as opposed to "interpretative science." 

 Every specific name is of itself an interpretation ; 

 "' Equus asinus " is a statement that the creature is 

 closely akin to " Equtis caballus.^^ The classification of 

 any group, and still more the classification of a whole 

 kingdom, contains a long chain of interpretations. 

 Modern systematic work — with which Sir Archdall 

 Reid must surely be ill acquainted — deals at every 

 step with "problems of heredity, evolution, develop- 

 ment, and the like." There may stHl be a few people 

 who confine their energies to pure description of the 

 objects in front of them; but why call them sys- 

 tematic zoologists or botanists? F. A. Bather. 



Experimental Geometry. 



Dr. Jeffreys (Nature, April 28, p. 267) claims that 

 "experimental geometry" is a contradiction in terms. 

 I protest vehemently. "Geometry" means the 

 measurement of the earth. How can you measure 

 the earth without experiment? It is "logical geo- 

 metry" that is the contradiction in terms; it is that 

 expression which has introduced all this confusion 

 between logic and experiment ; and it is the mathe- 

 maticians, not the experimenters, who have stolen the 

 word and perverted it from its proper meaning. 



Norman R. Campbell. 



19 Holland Park, W.ii. 



Italian Meteorites. 



As reference was made in Nature of March 31 

 (p. 149) to records of Italian aerolites, it may be noted 

 that there were fourteen falls of stones or earth in 

 central Italy recorded in forty years from 208-168 B.C. 

 It appears that the earth was then passing through 

 a region of aerolites. The references in Livy are . 

 under the years a.u.c. 545. 548, :;5o, 558, 559, 561, 



5641 567. o75. 579i 580, 583. 584, and .^85. ^ 



W. M. F. Petrie. 



5 Cannon Place, N.W.3. 



