362 



NATURE 



\Mar. 12, 1874 



however, be objected that the doctrine which Mr. Darwin else- 

 where inculcates,* and deems sufficient to account for the total 

 suppression of rudimentary ori;ans, viz., inheritance at earlier 

 periods of hie, is fa al to dystclcology as a prop to evolution — at 

 least in the case of long-lived species. And so it would be, were 

 not this principle of so shadowy an application that, while it is 

 perfectly legitimate to point to it as a possible cause of total sup- 

 pression in some cases, it would be simply absurd to argue that 

 such must be its effect in all. 



We next come to the Economy of Growth. Suppose an organ 

 to becomL- suddenly useless, this principle would at first cause its 

 rapid reduction. In proportion, however, as its presence ceases 

 to be injurious, the arresting process becomes slower and slower, 

 until a point is reached at which it is presumably nil. That 

 such a point of rest must somewhere be attained seems evident, 

 if we consider that the smaller the diminishing organ becomes 

 the less is it subject to the influence of the Economy of Growth. 

 In other words, when the organ undergoing reduction becomes 

 so minute relatively to the size of the animal (or, more correctly, 

 to the available store of nutrition), that the supply of nourishment 

 it requires is no longer perceived by the organism at large, it 

 then remains permanently of that size. "The economy of growth 

 will not account lor the complete or almost complete obliteration 

 of, for instance, a minute papilla of cellular tissue representing a 

 pistil, or of a microscopically minute nodule of bone representing 

 a ttioth ; "f anJ, the whole principle being one of relation, it is 

 a que^tion, for instance, whether the rudimentary digits of a 

 horse consume a greater rcla ive amount of nutrition than does 

 the " minute papilla." Besides, without entering in o details, I 

 think there is very good reason to believe that the Economy of 

 Growth is unable to reduce an organ which was originally large, 

 to the same absolute size as it can an organ which was originally 

 small. From all this it foUuw.s, that if the struggle for existence 

 were in any case so keen as to afford Selection {i.e.. Economy) 

 the opportunity of totally obliterating every !udiment.iry organ, 

 it seems probable that the species itself would require to become 

 extinct. 



Turning now to the last of the causes propounded by Mr. 

 Darwin, there can be no doubt that it is (theoretically) sufficient 

 to procure total obliteration. Forasmuch, however, as we can 

 never know in any given case whether or not the requisite con- 

 ditions have been supplied, — i.e. impoverished nutriment for an 

 enoimous length of time, — this newly added cause afTords no fur- 

 ther justification ior the old statement, that the theory of Natural 

 Selection fails to account for all the ficts of Dysteleology. 



The perusal of the last-mentioned thoughtful conception has 

 suggested to me the probable existence of another cause, having 

 a more general application ; but as it can never induce complete 

 suppression, I shall reserve it for the subject of another com- 

 munication. 



Mr. Mivart supposes that organs may become suddenly 

 aborted + ; but, apait from the weighty objections to this view,§ 

 there is no case on record, so far as I am aware, of an organ thus 

 becoming tvtally suppressed in any domestic species. A sport of 

 this kind always leaves a rudiment, and it is upon the analogy 

 of such sports alone that Mr. Mivart's argument is founded. 



Having now enumerated all the causes ever proposed by evo- 

 lutionists to account for the reduction of useless parts, it is 

 evident that we should antecedently expect to find innumerable 

 examples of such parts in the conditionofrudiments.il Indeed 

 the only difticulty is to account for that final disappearance of 

 organs which must, by any theory of evolution, be postulated to 

 have taken place. The solution is afforded by the exhaustive 

 contemplations of Mr. Darwin, for, whether or not we believe in 

 pangenesis, we cannot but deem it in the highest degree probable 



upon until the point of such exhaustion is attained ; but is it not open to 

 question whether this point can never be reached at all? It must de remem- 

 bered, too that in the case of wild species the effects of disease are always 

 associated with other reducing causes, so that here we may easily over-rate 

 the share it has in the work ; but in the case of domesticated species the 

 eHecls of disease are much more isolated (in consequence of tconomy of 

 Growth, etc., being, to a great extent, in abeyance) ; and here we find that 

 atrophy of disused parts, although at first very rapid, eventually does not 

 proceed to nearly so great an extent as it does in the case of wild species. 

 The question thus raised, however, is of no practical importance, since 

 whether or not disuse is the chief came of atrophy in species, there is no 

 doubt that atrophy accompanies disuse. 



* '* Variation." vol. ii. p. 80. 



t " Variation," vol. ii. p 397. 



t " Gene is of Species," 1st ct 



§ See " Origin," pp. 201—: 



II It is unnecessary to consider the toiiectivc action of these causes for a 

 miiment s reflecUon will now make it evident that none such exists below the 

 point at which the Economy of Growth ceases to be felt. 



cd. p. 103. 



that the influence of inheritance is not of unlimited duration. If so, 

 we have at once an adequate cause for the eventual destruction, 

 even in the embryo, of rudimentary parts ; but, as it is a cause 

 which would only act after an immense lapse of time, it would 

 have no influence until the original specific type had undergone a 

 considerable modification. Thus, the facts of dysteleology, far 

 from "cutting two ways," afford the strongest confirmation of the 

 natural selection theory ; for, as time is thus shown the chief 

 agent in the final destruction of rudiments, and as species are 

 always undergoing change, on the one hand we have an explana- 

 tion of the fact, that the greater the divergence of the specific 

 type from its original the fev.'er rudiments do we find of 

 organs characteristic of the latter, while on the other hand, the 

 less such divergence the grea'er the number of such rudiments — 

 a fact of which the necessary consequence is, that " with species 

 in a state o( nature, rudimentary organs are so extremely common 

 that scarcely one can be named which is wholly free from a 

 blemish of this nature." George J. Romanes 



The Action of the Heart 



Having replied to Mr Garrod's criticism of my "Locomo- 

 tion of Animals" (Nature, vol. ix. p. 2S1), I now wish to 

 show that the explanation given by him of the diastole of the 

 heart is not in accordance with fact. 



In a recent number of Nature (vol. ix. p. 282) I asked 

 Mr. Garr id to explan "how the left ventricle of the heart 

 opens after a vigr.rous contraction in which all tlie blood con- 

 tained in the ventricular civity is ejected and the ventricle 

 converted into a solid muscular mass, if not by a spontaneous 

 elongation of all its fibres." He replies: — "At first sight it 

 might seem that the active dilatation of the heart during the 

 diastole did depend on an inherent power in the muscular 

 fibres of the ventricles to elongate, but the peculi.rities of the 

 coronary circulation are quite sufficient to explain the phen imenon 

 without the introduction of so unnecessary a thetiry as that of 

 Dr. Pcttigrew. For in the heart when removed from the tjody, 

 as in the living body dur ng diastole, the injection of fluid 

 into the coronary vessels causes the whole heart to open up from 

 the congestion of the ventricular wall;-, and so produce the active 

 dilatation which is well known to occur " (Nature, vol. ix. 

 p. 301). 



Ttie explanation given by Mr. Garrod of the manner in which 

 the ventricles of the heart open up during the diastole is emi- 

 nently unsatisfactory. In fact it is no explanation at all. He 

 informs us that the active dilatation of the ventricles is due " to 

 peculiarities in the coronary circulation" . . . "for in the 

 heart when removed from the body the injection of fluid into the 

 coronary vessels causes the whole heart to open up from the 

 congestion of the ventricular walls, and so produce the active 

 dilatation which is well known to occur." 



Tlie coronary vessels, as everyone is aware, simply supply the 

 blood which nourishes the substance of the heart. There is no 

 peculiarity whatever in the circulation of the blood through them. 

 The blood flows through the coronary vessels in a more or less 

 steady stream as through all the other vessels of the body. In 

 other words the substance of the heart is full of blood during 

 the closure or systole of the ventricles, as well as during the 

 opening or diastole of the ventricles. The presence of the blood, 

 therefore, within the coronary vessels can exert no influence 

 in opening up or actively dilating the ventricles. This is proved 

 by direct experiment. If the heart be cut out of the living body 

 and the coronary vessels divided, the ventricles go on opening 

 and closing with the utmost regularity for protracted periods. 

 Here, however, the power which, according to Mr. Garrod, opens 

 the ventricles is inoperative. The same thing happens when the 

 heart is cut out of the body and the vessels laid open. If, 

 however, the ventricles open and close when the coronary vessels 

 are freely divided, and the blood which is said to distend or open 

 up the ventricles is allowed to escape from the cut surfaces, it is 

 quite clear that the blood pressure within the ventriciJar walls 

 can exert no influence whatever in producing the diastole. If 

 blood is not admitted into the coronary vessels, or if admitted 

 it is allowed fieely to escape, it cannot of course act as a dis- 

 tending medium. Allowing, however, for the sake of argument, 

 that the flow of blood through the vessels of the ventricles occa- 

 sioned the opening or dilatation of the ventricles, it is evident, 

 for the same reason, that the presence of the blood within the 

 \'entricular walls, from the fact that the blood is nearly constant 

 in quantity and virtually incompressible, would prevent the 

 closing or contraction of the ventricles. Mr. Garrod, I opine, is 



