182 Life and Letters of Francis GaUou 



42, Rutland Gate, S.W. Nov. 3/76. 



Mt dbab Darwin, It was truly kiud of you, to write ine with your own hand, a note of 

 warning about Balhiani ; but I do not use his statenients in any way, in my forthcoming memoir 

 which is to be road next Tuesday at the Anthropological Society. 



llie general line of it is this: 



First I start with the 4 postulates, in favour of which you have so strongly argued, and which 

 may reasonably be now taken for granted: — 



1. Organic units in ^'rent number. 



2. Germs of such units in still greater number and variety (existing smiunvhere). 



3. That undevelope<l germs do not perish ; but multiply and are transmissible. 



4. Organisation wholly depends on mutual affinities. 



From these 4 postulates, I logically deduce several results, one of which is the importiinco 

 and almost the neces.sity of double parentage in all complex organisations, and consequently of sex. 



Then I argue that we must not look upon those germs that achieve development as the main 

 sources of fertility; on the contrary, considering the far greater number of germs in the latent 

 state, the influence of the former, i.e. of the p>ersonal structure, is relatively insignificant. Nay 

 further, it is comparatively sterile, as the germ once fairly developed is passive; M'hile that 

 which remains latent continues to multiply. From this follows: — 



(1) The extremely small triinsniissibility of acquired modifications (to which I recur). 



(2) The fact that exceptional gifts are sometimes barely tninsniissible (here the sample 

 was over rich and drained the more fecund residue). 



(3) The fact of some diseases skipping one or more generations; (here the 8upjx)sition is 

 made of the genus of those diseases being jxjculiarly gregarious, hence the general 

 outbreak of them leaves but a small residuum which has not strength to break out in 

 the next generation, but being husbanded in a latent form, there multiplies and re- 

 covers strength to break out in the next or in a succeeding generation). 



Next, I go into the question of affinities and repulsions, which I put as necessarily numerous 

 and many-sided (while |)rofessing entire ignorance of their character) and I argue thence, a long 

 period of restless unsettlement in the newly fertilised ovum, accompanied as we know it to be, 

 with numerous segregations and segmentations in each of which the dominant germs achieve 

 development, while the residue is segregated to form the sexual elements. But I argue, that as 

 our experience of |»olitical and other segregations shows that they are never perfect, we are 

 justified in expecting that numerous alien germs will l)e lodged in everj' structure and that 

 specimens of all of them will lx> found in almost all parts of the body. In this way, I account 

 for the reproduction of lost parts, etc., as well as for the inheritance of all peculiarities that 

 had been congenital in an ancestor. 



I then consider the cases of inheritance of what had ))een non-congenital in an ancestor, but 

 acquired by him. I show that the deduction usually made, that the structure reacts on the 

 sexual elements, is not justified by the evidence of adaptivity of race, whttn this depends on 

 conditions which nr.l equally on all parts of tlii; body. My re^ison is, that since the .same agents 

 (viz. the genns) are concerned Iwth in growth and in repro<luction, the conditions that would 

 modify the one, would simultaneously nio<lify the other ; hence they would l>e collaterally affected 

 and the apparent inheritance is not a case of iidieritance at all, in the strict sense of the word. 

 Nay the progress may b<!gin to varj' under cliange<l conditions nooufr than the jmrent (as in 

 the hair or fleece of the young of dogs and sheep, transported to the tropics). 



As regards Brown-Hequani's guinea pigs; — if I rightly understand and am informed of his 

 ex|>eriment, it ia open to fatal objection. The guinea-pigs that were opcrate<l on app<vir to have 

 been kept separate from the rest. If so, wo should expect the young sometimes to have convul- 

 sive attacks from mere imitation, just as we should ex|Kx;t of children brought up in a ward of 

 epileptic patients, or among hysterical people (revivals, dancing mania etc.). Besides, there is 

 nut the least evidence that the mutilation of the .spinal marrow, on which the parentjd epilepsy 

 primarily depemlod, was inherite*!. I alsf) di.sparage much other evidence of the inheritance of 

 ac<|uin-d mixiifications, l(^aving but a vei-j' small re.sidue to accept. For this residue, I account 

 by supposing the germs thrown ofl' liy the struclun- during its regular reparation, to frequently 

 find their way into the circulation and some of the w occasionally to reach the sexual elements and 

 to Ixicome lodged and naturalise<l thei-e, either by finding an unoccupied place or by dishxlging 

 others, like immigrants into an organi8<>d society, coming from a foreign country. Thus I occoutit 

 both for the fact, and for the great rarity and slown<^8S of the inheritance of accjuired modifications. 



