Correftpondnice tinth C/iorfen IJaririti 103 



Before we turn to the Nature letters, we must notr ..lu- ..i i».. i...iiii^, 

 iiaiiu'ly: 



{(i) Galtoii kept Darwin fully informed of the traiiHfusion of blood ex- 

 perinuMits, and furtiier statexl their In'arin^ on Pangenesis. 



(M Darwin clearly made throughout the experiments hints for their 

 niodihcation and extension even to otrier sj)ecie8. 



((■) CJalton's letters and paper are not conipatil)le with Dar\Mn ri;i\iii^ ;iL 

 any time warned him that the circulation oftlie hiood was not a necessary 

 factor in his own theory. 



{(I) Oalton's words on p. 3!)5 of his memoir cited hy Darwin were too 

 sweeping, l)ut at the same time they were actually (pialitied hy what he 

 wrote on p. 404 that "the doctrine of Pangenesis, pure and simple, <«.>i / hnve. 

 intcrjiri'ted it', is incorrect." 



Letter of Cliarlos Dnrwiii in Nuturi', April 21, lt<71. 



"Panj^enesis." Tn a pnpor, reiid March 30, 1871, Ix-forn fho Royal Society, and just 

 pulilish(><l in the Proceeilings, Mr (taltoii gives the results of liia interesting ex|)erinients on the 

 inter-transfusion of the bliKxl of distinct varietit« of rabbits. These exjierinientfl were (indertaken 

 to test whether there was any truth in my provisional hypothesis of Pangenesis. Mr Oalton, in 

 recapitulating "the cartiinal points," sjiys that the gemniules are supp<«e<l "to swann in the 

 blood." Me enlarges on this head, and remarks, "Under Mr Darwin's theory, the gemniules in 

 oaeii individual must, therefore, l)e looked upon as entozoa of iiis blood," etc. Now, in the 

 chnpter on Pangenesis in my "Variation of Animals and Plants under Domestication," I have 

 not said one word about tlie blood, or about any fluid proper to any eirculatii l It is, 



indeed, obvious that the presence of gemniules in the blood can form no neei- • i of my 



hy()othesis; for I refer in illustration of it to the lowest animals, such as the Protozoa, which 

 do not possess blood or any vessels; and I refer to plants in which the fluid, when present in 

 the vessels, cannot be considered as true blood'. The fundamental laws of growth, repnxluction, 

 inheritance, etc., are so closely similar throughout the whole organic kingdom, that the nicAns 

 by which the geninmles (assuming for the moment their existence) are ditFusetl thmugh the body, 

 would prolwbly Ih' the same in all beings; therefore the means can hartlly be diffusion through 

 the bloo<l. Nevertheless, when I first heard of Mr fJalton's expi>riinents, I did not sufliciently 

 n'fli-ct on the subject, and saw not the diHiculty of believing in the presence of geninmles in the 

 bloiKl. I have said (Variation, etc., vol. ii, p. 379) that "the gemmide.s in each organism must 

 be thoroughly diffused; nor does this seem improbable, considering their rainutenes.s, and the 

 steady circulation of fluids throughout the Ixidy.'' Hut when I used these latter words and other 

 similar one.s, I presume that I wa,s thinking of the diffusion ot' the gemniules thmugh the tissues, 

 or from cell to cell, independently of the prt'sence of ve.ssels, — as in the remarkaMe exjierimentd 

 by Dr Bence Jones, in whicli chemical elements absorbed by the stomach were <lete<-te<l in the 

 course of .some minutes in the crystalline lens of the eye; or again as in the r<'peAt4'd loss of 

 colour and it« recovery after a few days by the hair, in the singular case of a neuralgic lady 

 recorded by Mr Pagt^t. Nor can it be objecte<l that the gemrfiules could not pa.ss thmugh tissues 

 or cell-walls, for the contents of each jMiUen grain have to pass thi-ough the coats, lH)th of the 

 pollen tul)e and embryonic sack. 1 may add, with resp(>ct to the pa.ssage of fluids thmugh mem- 

 brane, that they pa,ss from cell to cell in the absorbing hairs of the roots of living plants at a 

 rate, as I have myself observed under the microscope, which is truly surf)rising. 



When, therefore, Mr (ialton concludes from the fact that rabbits of one variety, with a 

 large proportion of the blcMxl of another variety in their veins, do not produce niongreli.sed off- 

 spring, that the hypothesis of Pangenesis is false, it seems to me that his conclusion is a little 



' I have itnlicise<l these woi-ds to emphasise Oalton's attitude. 



' Note by the biographer. It would seem feasible to test the theory of pangenesis in the 

 case of plants by considering the results obtained from the seeds of grafted and non-grafted 

 plants of the same species. 



21— a 



