Oct. 24, 1889] 



NATURE 



621 



thereby causing the sudden production of large volumes of gases 

 at the ordinary temperature. 



In answer to Mr. Griffith's query, I may state that the two 

 trees are 34 yards apart ; that there is no other tree in a direct 

 line between them, though there are two about 4 yards from this 

 line, and about midway between them ; that the trees are cer- 

 tainly not isolated in any way, since there are fifteen trees within 

 less than 34 yards of one of them, and about the same number 

 within the same distance of the other. 



48 Bryanston Square. Spencer Pickering. 



Yew Trees in Berks. 



A cpMMUNlCATlON from Mr. Walter Money respecting two 

 yew trees which were planted in the churchyard of Basildon, 

 Berks, by Charles, Lord Fane, in 1726, has appeared lately in 

 some of the papers {North Wilts Herald, October 4, 1889, and 

 Standard), in which he refers to the dimensions recorded in the 

 parish register, taken in 1780 and 1796, and again by my father 

 in 1834. He adds his own observations on the growth taken 

 this year. As I happen to have the original notes made by the 

 late Prof. 1. S. Henslow, dated " 1834, August," it may be 

 not uninteresting to record them. He writes as follows : — 



" Measurements of yew trees at Basildon Churchyard, planted 

 in 1 726 ; taken near the ground : 



Ft. In. 



Tree to south, 1780 6 3 1 According to 



1796 3 6 J Register. 



1834 8 9 I rr s H 1 



„ (at 4 feet) 6 \o\] U- ^- "•-' 

 [1889 9 10 Mr. Money] 



Tree to north [1780 and 1796 not recorded in register] : 



Ft. In. 

 9 2i 



Roots lately in- 'j 



juredby digging \ 1834 



graves. J \ [J. S. H.] 



„ (at 4 feet) 6 9I 

 [1889 9 6 Mr. Money] 



"From the three observations of 1780, 1796, and 1834, it 

 would appear that the period of rapid growth stopped about 

 1796; but it seems probable that the measurement here is 

 somewhat too great compared with that of 1780, as well as 

 with that of 1834 ; for 



Growth 



Ft. In. Lines. 



Lines. 



Years. Lines 



to per ann. 



1780 ...63 = 900 gives 300 diam. of gr. in 54, i.e. Sh 

 1796 ...23 = 324 ,, 108 „ „ l6, „ 6| 



"Allowing this measurement to be wrong by 6 inches, it will 

 reduce it to a greater probability also with that of 1834 ; and 

 we shall have — 



Growth 



to 



1796 



1834 

 [1889 



Ft. In. Lines. 



Lines. 



Years. Lines 

 per ann. 

 19 = 252 gives 84 diam. of gr. in 16, i.e. 5-; 

 9 = 108 ,, 36 ,, „ 38, „ I 



I I = 156 „ 52 „ ,, 55, „ I] 



"N.B. — The increase between 1780 and 1796 is too great, 

 supposing the same parts to have been measured ; and between 

 1796 and 1834 it is too little ; therefore 1796 either took in too 

 much of the circumference of the roots, or perhaps 1780 a little 

 above them. Possibly the soil had become somewhat raised 

 since 1796. 



[Since 1834 the growth for the last fifty-five years will be seen 

 to be exactly the same per annum, or i line.] 



[With regard to the rate of increase at a height of 4 feet from 

 the ground, he adds the following additional note.] 



"Now the rate of increase of 4 feet from the ground is 

 slower than that near the root, upon the whole, in the propor- 

 tion of one-fourth, nearly. Taking, therefore, this fact with the 

 indications given above, we may averse the growth of the stem 

 at 4 feet in the following way : — 



"Diameter at 4 feet = ^-^° lines = 330 (in 1834).. " Dividing 



* 3 



this by the age, or 108 years, it gives 3 lines per annum nearly. 



"Also 1780 to 1796 gives 84 lines for 16 years, i.e. 5 lines 

 per annum. 



"As it seems not to have grown much in the last twenty- 

 eight years {i.e. up to 1834), if we allow i line for this period, 



and distribute for the eighty years of rapid growth, we get the 

 following result ; thus : — 



First 20 years at 3^ lines = 70 ') 



,, 40 ,, 4 ,, = 160 > Young growth. 



„ 20 „ 3 „ = 60) 



,,28 ,, i| ,, = 42 Settled period." 



George Henslow. 



Maxwell's " Electricity and Magnetism." 



There is apparently a trifling slip in § 360 of Maxwell's 

 " Electricity and Magnetism." The ratio of the resistance of 

 pure iron at 100° C. to the resistance at 0° C. is there stated to 

 lie I •645. This ratio is evidently calculated from the results 

 given in Matthiesen's paper on the influence of temperature 

 on the electric conducting power of thallium and iron (Proc. 

 Roy. Soc, 1862-63). The true ratio for pure iron annealed 

 in hydrogen is i'6255. The other ratios mentioned in the 

 paragraph are correctly deduced. 



Herbert Tomlinson. 



King's College, Strand, October 12. 



AN EXAMINATION OF SOME POINTS IN 

 PROF. WEISMANN'S THEORY OF HEREDITY.'^ 



PROF. WEISMANN'S views on heredity and allied 

 phenomena have met with such general acceptance 

 that I feel it to be presumptuous on my part to attempt 

 any criticism of them. I cannot but think, however, that 

 a statement of the difficulties which they present to me, 

 and of the inconsistencies which appear to exist in the 

 argument, may be of value, not indeed as a refutation, 

 but as drawing attention to those points which seem to 

 require further elucidation. 



It will be necessary for me to state Prof. Weismann's 

 argument, and I shall endeavour, in so doing, to represent 

 it as fully and as fairly as my apprehension of it will admit, 

 and as far as possible in his own words. But this is a 

 matter of no small difficulty, inasmuch as the argument 

 has to be traced through a number of separate essays, . 

 even though these essays have been collected into one 

 volume and translated into English. All the references 

 which I make relate to the English edition.^ ^ 



The fundamental fact upon which the whole argument 

 is based, and which Prof. Weismann appears to have 

 fully established, is that the body of unicellular organisms 

 (monoplastides), as also that of undifferentiated multi- 

 cellular organisms (homoplastides), is immortal, at any 

 rate potentially. This position is clearly stated in the 

 following passage (p. 25) : — 



"The process of fission in the Amoeba has been recently 

 much discussed, and I am well aware that the life of the 

 individual is generally believed to come to an end with the 

 division which gives rise to two new individuals, as if death and 

 reproduction were the same thing. But the process cannot 

 truly be called death. Where is the dead body? What is it 

 that dies ? Nothing dies ; the body of the animal only divides 

 into two similar parts, possessing the same constitution." 



Death is, on the contrary, a characteristic feature of 

 differentiated multicellular organisms (heteroplastides) ; 

 but even in these forms there is still an immortal part, 

 for the reproductive cells which develop into new indi- 

 viduals are evidently as potentially immortal as the 

 Amoeba. In these higher organisms, therefore, the mortal 

 cells are to be distinguished from the immortal. This 

 distinction is drawn by Prof. Weismann as follows 

 (p. 122) :— 



" It is necessary to distinguish between the mortal and the 

 immortal part of the individual — the body in its narrow sense' 

 {soma) and the germ-cells. Death only affects the former ; the 



' This paper is an expansion of some remarks contributed to the discus- 

 sion on " The Transmission of Acquired Characters," which took place in 

 Section D during the recent meeting of the British Association at Newcastle. 



^ Weismann, "'On Heredity " (O.vford : Clarendon Press, 1889). 



