4i6 



NATURE 



{March 6, 1890 



tuitists," and is "irrational." A more baseless charge was never 

 yet made in controversy, nor a more obvious attempt to alter the 

 terms of discussion so as to give some appearance of plausibility 

 to a lost cause. The Duke, in fact, now at length tells us that 

 /le does not mean by " acquired characters " what 7ue mean. 

 Why then did he " interpolate " his remarks on the subject and 

 make use of the term ? 



If the meaning which the phrase has for the scientific world 

 generally be insisted upon, we are now, it appears, to understand 

 that the Duke of Argyll agrees with us : what Ti>e mean by 

 •'acquired characters" are not, he admits, shown to be trans- 

 mitted. 



" Fortuitists," the Duke says, "have invented a new verbal 

 definition of what they mean by 'acquired.' " I have shown at 

 the commencement of this letter that the term " acquired " is used 

 to-day as it was by Lamarck. To the Duke this meaning is 

 " new " — because he has either never read or has forgotten his 

 Lamarck. If this be so, the Duke has been writing very freely 

 about a subject with which his acquaintance is very small. The 

 alternatives are as clear as possible : either the Duke of Argyll 

 knew the significance of the term "acquired characters" as em- 

 ployed by Lamarck, in which case it would have been impossible 

 that he should charge those whom he calls " fortuitists " with 

 having invented a new verbal definition of what they mean by 

 " acquired " ; or he did not know Lamarck's use of the phrase, 

 and was therefore not qualified to offer an opinion in the dis- 

 cussion, nor to press his " beliefs" and "position " upon public 

 attention. 



I have no time and you have no space to devote to a full 

 exposure of the character of other assertions made in the Duke 

 of Argyll's "statement of his position" which are as reckless 

 and demonstrably erroneous as that concerning the meaning of 

 the term "acquired." 



Perhaps the most flagrant of these is the assertion that ' ' the 

 theory of Darwin is essentially unphilosophical in so far as it 

 ascribes the phenomena of variation to pure accident or fortuity " 

 (paragraph 4). Of course the Duke cannot be acquainted with the 

 following passage from the " Origin of Species," sixth edition, 

 p. 106 ; but if he has to plead ignorance of the writings not only of 

 Lamarck, but also of Darwin, what is the value of his opinions 

 and beliefs on Lamarckism and Darwinism ? The words of 

 Mr. Darwin referred to are these : — " I have hitherto sometimes 

 spoken as if the variations, so common and multiform with 

 organic beings under domestication, and in a lesser degree with 

 those under nature, were due to chance. This, of course, is a 

 wholly incorrect expression, but it serves to acknowledge plainly 

 our ignorance of the cause of each particular variation. " 



Whatever meaning the Duke may attach to the word 

 "fortuity," it is mere empty abuse on his part to call the 

 later Darwinians "fortuitists," and still less justifiable to insinu- 

 ate that their investigations and conclusions are not guided by a 

 simple desire to arrive at truth, but by the intention of propping 

 up a worship of Fortuity. It is natural for the Duke to suppose 

 it impossible to write on Darwinism without some kind of theo- 

 logical bias. 



In conclusion, I venture to point out that the Duke of Argyll 

 has (l) failed to cite facts in support of his assertions of belief 

 in "prophetic germs," and "transmission of acquired cha- 

 racters " when challenged to do so ; (2) that he displays ignor- 

 ance of two of the most important passages in the works of 

 Lamarck and of Darwin, whom he nevertheless criticizes, and 

 in consequence of his ignorance completely, though uninten- 

 tionally, misrepresents ; and (3) that he has introduced into these 

 columns a method of treating the opinions of scientific men, viz. 

 by insinuation of motive and by rhetorical abuse, which, though 

 possibly congenial to a politician, are highly objectionable in the 

 arena of scientific discussion. 



February 22. E. Ray Lankester. 



Physical Properties of Water. 



As you inform me that my anonymous critic {ati^e, p. 361) 

 does not intend to avail himself of the opportunity I gave him 

 (through you) of correcting his misstatements about my Challenger 

 Report, I must ask to be permitted to correct them myself. 



(i) There is nothing whatever in my Report to justify the 

 critic's statement that I '■'had never heard 0} Ya.n der Waals' 

 work . . . till the end of the year 1888." Yet this is made the 

 basis of an elaborate attack on me ! 



What I did say was to the effect that I was not aware, till Dr. 



Du Bois told me, that Van der Waals had given numerical esti- 

 mates of the value of Laplace's K. I had long known, from 

 the papers of Clerk-Maxwell and Clausius, the main features of 

 Van der Waals' investigation. But I also knew that Maxwell 

 had shown it to be theoretically unsound ; and that Clausius 

 had taken the liberty of treating its chief formula as a mere 

 empirical expression, by modifying its terms so as to make it 

 better fit Andrews' data. This paper of Clausius is apparently 

 unknown to my critic, as is also my own attempt to establish 

 (on defensible grounds) a formula somewhat similar to that of 

 Van der Waals. 



(2) I said nothing whatever about the " Volume of Matter in 

 unit volume of Water." Hence the critic's statement, " Prof. 

 Tait's value is 0717," is simply without foundation. 



I merely said that the empirical formula 



p{v - o) = constant, 



if assumed to hold for all pressures, shows that o is the volume 

 when the pressure is infinite. I still believe that to be the 

 case. If not, Algebra must have changed considerably since I 

 learned it. 



My critic speaks of a totally different thing (with which I was 

 not concerned), which may be 0/4 or 0/4 ^2, or (as I think is 

 more plausible) a/8. But he says that liquids can be compressed 

 to o*2 or 0'3 of their bulk at ordinary temperatures and pres- 

 sures. I was, and remain, under the impression that this could 

 be done only at absolute zero, and then no compression is 

 required. 



There are other misrepresentations of my statements, quite as 

 grave as those cited. But it would be tedious to examine them 

 all. I have no objection to a savage review, anonymous or not; 

 on the essential condition, however, that it he fair. It is clear 

 from what I have shown that this essential condition is absent. 



But my critic, when his statements are accurate, finds fault 

 with the form of my work. I will take two examples of this 

 kind, and examine them. 



(3) He blames me for not using C.G.S. units. The Chal- 

 lenger Reports are, as a rule, written in terms ' ' understanded 

 of nautical men. I wonder what such men would have said 

 of me, in their simple but emphatic vernacular, if I had spoken 

 of a pressure of 154,432,200 C.G.S. units, when I meant what 

 they call a "ton" ; or, say, of 185,230 C.G.S. units, when I 

 meant a " naut." 



(4) I am next blamed for "mixing units." 



I should think that if we could find a formula expressing, in 

 terms of a man's age, the average rate at which he can run, say 

 for instance 



^^ _ A,ar(B - x) 

 X- + (^ 



even my critic would express A in feet per second, and take x as 

 the mere number denotmg the age in years. Would he, alone 

 in all the world, insist on expressing x as denoting the age in 

 seconds in order to prevent what he calls the mixing of units? 

 This is a case precisely parallel to the one in question. 



Generally, 1 would remark that my critic seems to have 

 written much more for the purpose of displaying his own 

 knowledge than of telling the reader what my Report contains. 

 For at least three of the most important things in my Report 

 are not even alluded to : — the compressibility of mercury, the 

 nature of Amagat's grand improvement of the Alanomctre 

 Desgoffes, and (most particularly) the discussion of the wonder- 

 ful formula for the compressibility of water given in the 

 splendid publications of the Bureau International. 



P. G. Tait- 



The last V9lume of the Challenger ReYtorts contains papers on 

 various branches of science. The review which appeared in 

 Nature was not the work of one writer, and was therefore not 

 signed, but I have no desire to avoid taking full responsibility 

 for the part of which I am the author. 



It will be convenient to reply to Prof. Tait in paragraphs 

 numbered to correspond with his own. 



(i) Of course I fully accept Prof. Tait's account of his know- 

 ledge of Van der Waals' theory at the time when his Challenger 

 Report was written, but I entirely dissent from his statement 

 that what he said about it in the Addendum referred to in the 

 review was "to the effect " described above. 



It is hardly possible to do justice to my own case without 

 quoting freely, but I will compress as much as possible. He 



II 



