NATURE 



[December 31, 189] 



The pigment is freely soluble in hot water, though quite in- 

 soluble in cold water, and in most organic solvents. Its 

 aqueous solution is strongly acid to litmus ; and, though it 

 appears to be quite innocuous to frogs when injected under the 

 skin, it may well be ungrateful to the ranine palate. At the 

 «ame time it must be noted in this regard that its solubility in 

 the secretions of the frog's mouth is but very slight. 



The substance is, as I have shown, undoubtedly a derivative 

 of uric acid, yielding the latter body as one of its products of 

 hydrolysis. It gives the murexide reaction direct. It forms 

 quite definite salts with metals, its compounds with the alkalies 

 being soluble bodies. 



Having regard to the wide-spread presence of the body in the 

 scales of diurnal Lepidoptera, I have ventured to call it lepi- 

 dotic acid. In its physical properties it closely resembles 

 mycomelic acid, a yellow derivative of uric acid ; and, in my 

 original paper, I ventured to suggest a formula for the body. I 

 hope shortly to publish a more complete account of the subject, 

 and to assign a formula to lepidotic acid based upon fuller 

 evidence. Meanwhile, in common with many others of your 

 readers, I am looking forward to the appearance of Mr, 

 Beddard's book. The literature of the subject of animal 

 coloration is not easily accessible, and a text-book thereon will 

 be a valuable acquisition. We have, it is true, the interesting 

 \Aork of Mr. Poulton ; but the subject is there treated from what 

 is, perhaps, a somewhat limited standpoint. 



F. GowLAND Hopkins. 



Sir Wm. Gull Research Laboratory, 

 Guy's Hospital, December i6. 



The Chromosphere Line A 6676*9. 



In response to Father Cortie's implied question as to the 

 identification of this line as belonging to the spectrum of iron, 

 I wouldrefer him to Appendix Got Roscoe's lectures on " Spec- 

 trum Analysis " (third edition). It is an extract from a joint 

 paper by Angstrom and Thalen, giving a list of several hundred 

 (then) new identifications ; among them appears K 654'3, 

 ascribed to iron. 



The original memoir was presented to the Stockholm Academy 

 of Sciences in February 1865, and an English translation of it 

 appeared the next year. I am unable to assign any reason why 

 many of the identifications given in this memoir fail to appear 

 in the map published three years later ; but they do, and 

 K 654'3 is among the missing. C A. Young. 



Princeton, N.J., U.S., December 15. 



Grafts and Heredity. 



I HAD not thought of grafts when I wrote my paper, and I 

 have to thank Mr. Beeby for reminding me of an excellent 

 illustration of my views ; though I cannot gather from his letter 

 whether he considers the "individuality" for which he con- 

 tends to be represented by matter or force. Adopting his 

 phrase I would apply it to both. The material form, e.g., of the 

 leaf of the scion, is due to molecular motion, set up by a 

 group of forces acting in a way peculiar to the life of the scion ; 

 which /tjrc^j-, together with the resulting /c^rw, constitute its in- 

 dividuality — somewhat as a man is known by his mental and 

 moral characters as v\ ell as by his face. 



Now, no two individual plants could be fed more alike than a 

 stock and its grafted scion ; since they both receive identically 

 the same food through the roots of the former. All I contend 

 for is, therefore, that it would seem to be more probable that the 

 organic molecules constructed out of this food are all alike, only 

 differently arranged in the leaf of the scion and in that of the 

 stock respectively. These arrangements must be due to mole- 

 cular forces ; while it is difficult to conceive in one's mind how 

 any special kinds of matter can be concerned in the construction 

 of the special forms of leaves ; to say nothing of the total want 

 of evidence of the existence of germ- or other plasm. 



There is, however, a deeper question still which Mr. 

 Croll asked: — "What deterniines molecular motion?"^ 

 He observed that although physical forces are not only in- 

 terchangeable but can pass into those which, for want of a 

 better expression, we may call vital energies ; yet, as he says, 

 nothing we know of in the properties of physical forces can 



^ " What Determines Molecular Motion ? — The Fundamental Problem of 

 Nature" (,Phil. Mag., July 1872). 



throw the smallest degree of light upon the above question. 

 There is always, he adds, the " object " which runs through the 

 whole of organized nature ; which cannot be accounted for by 

 means of the known properties of physical forces. In concluding 

 bis paper he says : — " If one plant or animal differs from 

 another, or the parent from the child [and, we may add, the 

 scion from the stock], it is because in the building up process the 

 determinations of molecular motion were different in the two 

 cases ; and the true and fundamental ground of the difference 

 must be sought for in the cause of the determination of molecu- 

 lar motion. Here, in this region, the doctrine of natural selec- 

 tion and the struggle for existence can afford no more light on 

 the matter than the fortuitous concourse of atoms and theatomical 

 philosophy of the ancients." This observation seems to agree 

 with the following remark of Sir J. D. Hooker on the origin of 

 secretory glands ol Nepenthes : — " The subsequent differentiation 

 of the secretory organs of the pitcher into aqueous, saccharine, 

 and acid would follow pari passu with the evolution of the 

 pitcher iiself, according to those mysterious laws which re-ult in 

 the correlation of organs and functions throughout the kingdoms 

 of Nature ; which, in my apprehension, transcend in wonder and 

 interest those of evolution and the. origin of species." ^ 



The nea'-est approach to an answer to Mr. C roll's question is, 

 as it seems to me (though it be but cutting the Gordian knot 

 after all), that there exists a responsive and adaptive poiver 

 inherent in living protoplasm which is called into action by 

 external forces ; so that by a change of environment — especially 

 if the old and the new one be strongly contrasted — a plant, as a 

 rule, at once begins to alter its structure so as to re-establish 

 equilibrium with its new surroundings ; and further, if these be 

 maintained long enough, the altered btructures becooie fixed and 

 hereditary, while more or less of readaptation can commence 

 again at any time. 



We can no more discover the ultimate cause of this power 

 which determines or directs molecular motion in living beings, 

 than we can that of crystallization or gravity, reflex action or 

 instinct. Innumerable facts, however, justify the full recognition 

 of its existence. 



To apply this to grafts. It is obvious that, whatever determines 

 the molecular motion in forming the leaf of the scion, it is differ- 

 ent from that which determines the molecular motion in forming 

 the leaf of the stock, since the resulting forms of the leaves are 

 different ; and it is just this ultimate determining poiuer, which 

 is unknown and apparently unknowable, which characterizes 

 the individuality of the scion on the one hand, and of the stock 

 on the other. Form is but the outward and visible expression 

 of this power. It is this, too, which underlies the responsiveness 

 of protoplasm, and determines a new form in adaptation to, or 

 in equilibrium with, a changed environment. 



George Henslow. 



Mental Arithmetic. 



The very simple method of multiplying large numbers, 

 published in Nature (p. 78) by Mr. Clive Cuthbertson, is 

 mentioned by Pappus, Book II. (ed. Hultsch), 2-29, as an 

 invention of Apollonius. The same method was known to the 

 Hindoos under the name Vajrabhyasa (Algebra with Arithmetic 

 and Mensuration from the Sanskrit Brahmegupta and Bhascara, 

 translated l.y H. Th. Colebrooke, London, 1817). 



The method may be enlarged to multiplying three and even 

 more numbers all at once in the following manner :— 



(100^1 + 10^1 + iTj) (100^2 -I- iob.2 + c.,)(icoa3 + 10^3 -f ^3) = 

 c^c^c^ 

 + 10(^1^2^3 + ^^2^3^! + Vi^a) 

 -1- \o-(a-^c^c^ -^ ao^siTi H- a^c-^c^ 

 + h^-^z + ^•ih<=i + b-ib^c^) 

 + Io3(aj[V3 + V2] + «2[^3^1 + '^I'^sl 

 + «3['^l'^2 + Vl] + hl'-J>^ 



+ io*{a.^a^^ + a^.jC^ + a^a^c^ 

 + «lV3 + «2*3'^l + ^s^i'^a) 

 + lo^^a^a^b^ + a^a^b^ -f a.^a^b^} 

 + \&a-^a.^a^. 



NO. 1 157, VOL. 45] 



' Address to the Department of Zoology and Botany of the British Associa- 

 tion, Belfast, 1874. 



