164 Life ami Letters of Francis (ialton 



hastv. His words are, "I Imvi- now mn<li' exp<!riiiiontn of traiiKfusioii and cros8-cin;ulation on 

 a large scale in rabbits, and have arrive<l at delinite rexuiu, ncgativinji;, in my opinion, beyond 

 all doubt the truth of the doctrine of Pangenesis." If Mr Gallon could have proved that the 

 reproductive elements were contained in the blood of the higher aninmls, and were merely 

 separated or collectetl by the reproductive glands, he would have miwle a most important 

 physiological discovery. As it is, 1 think every one will admit tiiat his i'X|K'riuients are extremely 

 curious, and that lie deserves the highe.st credit for his ingenuity and p'rseverance. Ct it does 

 not appear to me that Pangenesis has, as yet, received its death blow ; though, from presenting 

 80 many vulnerable points, its life is always in jeopardy; and this is my excuse for having said 

 • few words in its defence. Charles Darwin. 



Letter of Francis Galton in Nature, May 4th, 1871. 



"Pangenesis." It appears from Mr Darwin's letter to you in last week's Naturt, that the 

 views contradicted by my experiments, published in the recent numl)er of the "Proceedings of 

 the Royal Sixjiet}'," differ from those he entertained. Nevertheless, 1 think they are what his 

 publishe<l account of Pangenesis (Animals, etc., under Domestication, ii, 374, 379) are most 

 likely to convey to the mind of a rea<ler. The ambiguity is due to an inappropriate use of three 

 separate words in the only two sentences wiiich imply (for there are none which tell us anything 

 definite about) the habitat of the Pangenetic gennnules; the woids are "circulate," "freely," and 

 "diffused." The proper meaning of circulation is evident enough — it is a re-entering movement. 

 Nothing can justly be .said Ui circulate which does not return, after a while, to a former position. 

 In a circulating library, books return and are re-issu(xl. Coin is said to circulate, because it 

 comes back into the same hands in the interchange of business. A story circulates, when a 

 person hears it repeated over and over again in society. Blood has an undoubted claim to be 

 called a circulating fluid, and when that phrase is used, bItKxi is always meant. I understood 

 Mr Darwin to speak of blood when he usetl the ])hra.se.s "circulating fr<K>ly," and "the steady 

 circulation of fluids," especially as the other words "freely" and "diffusion" encounigwl the idea. 

 But it now seems that by circulation he nicAnt "dispersion," which is a totally difFerent concep- 

 tion. Probably he used the word with some allusion to the fact of the dispersion having Ix'en 

 carried on by eddying, not necessarily circulating, currents. Next, as to the word "fn-ely." 

 Mr Darwin says in his letter that he supposes the gemmules Ui pass through the solid walls of 

 the tissues and cells, this is incompatible with the phra.se "circulate freely." Freely means 

 "without retardation"; as we might sjiy that small fish can swim freely through the larger 

 meshes of a net; now, it is impossible to suppose gemmules to pass through solid tissue without 

 any retardation. "Freely" would be strictly applicable to gemmules drifting along with the 

 stream of the blood, and it was in that sense I interpreted it. I^astly, I find fault with the use 

 of the word "diffused" which applies to movement in or with fluid.s, and is inappi-opriate to the 

 action I have just descril>e<l of solid Iwring it« way through solid. If Mr Darwin had given in 

 his work an additional i)ariigrapli or two to a description of the whei-ealxjuts of the gennnules 

 which, 1 must remark, is a cardinal point of his theory, my nii.sappreheiision of his meaning 

 could haixlly have occurred without more hesitancy than I experienced, but I certainly felt and 

 endeavoured to express in my memoir some shade of doubt; as in the phrase, p. 404, "that the 

 doctrine of Pangenesis, pure and simple, as I Imve interpreted it, is incorrect." 



As I now understanil Mr Darwin's meaning, the first passage (ii, 374), which misled me, 



and which stands: " minute ^anules which circulate freely throughout the system" 



should be understood as "minute granules which arc di.sf>ersed thoroughly and are in 



continual movement throughout the system"; and the second pas.sage (ii, 379), which now stands: 

 "The gemmules in each organism must l>e thoroughly diffused; nor does this seem improbable, 



considering the st<yuly circulation of fluids throughout the Innly," should l)c understood as 



follows: "The gemmules in each organism must l)ediN(>er8edall over it, in thorough intermixture'; 



' In later editions of his book, Darwin replaced "circulate freely" by "are dispersed through- 

 out the whole system" and he cancelled the words that this diffusion was not "improljable 

 considering the steady circulation of fluids throughout the Ixxly." But elements "dispersed 

 throughout the whole system" surely should have appeared in the blood. In a footnote to his 

 later editions (1H75, ii, p. 350) Darwin admits that he should have expected to find gemmules 

 in the blood "but this is no neceasary jxirt of the hypothesis." 



