To Leonard Jenyns   17 October [1846]

Down Farnborough Kent

Oct 17th.

Dear Jenyns

I have taken a most ungrateful length of time in thanking you for your very kind present of your Observations.1 But I happened to have had in hand several other books & have finished yours only a few days ago. I found it very pleasant reading & many of your facts interested me much: I think I was more interested, which is odd, with your notes on some of the lower animals than on the higher ones. The introduction struck me as very good; but this is what I expected, for I well remember being quite delighted with a preliminary essay to the first number of the Annals of N. History.2

I missed one discussion, & think myself illused, for I remember your saying you would make some remarks on the weather & Barometer,3 as a guide for the ignorant in prediction. I had, also, hoped to have perhaps met with some remarks on the amount of variation in our common species: Andrew Smith once declared he would get some hundreds of specimens of larks & sparrows from all parts of Great Britain & see whether with finest measurements he cd detect any propor-tional variations in beaks or limbs &c. This point interests me from having lately been skimming over the absurdly opposite conclusions of Glöger4 & Brehm;5 the one making half-a dozen species out of every common bird & the other turning so many reputed species into one. Have you ever done anything of this kind; or have you ever studied Gloger’s or Brehm’s works?6

I was interested by your account of the Martins, for I had just before been utterly perplexed by noticing just such a proceeding as you describe; I counted seven one day lately visiting a single nest & sticking dirt on the adjoining wall.7 I may mention that I once saw some squirrels eagerly splitting those little semi-transparent spherical galls on the back of oak-leaves, for the maggot within; so that they are insectivorous.— A Cychrus rostratus once squirted into my eye & gave me extreme pain; & I must tell you what happened to me on the banks of the Cam in my early entomological days; under a piece of bark I found two carabi (I forget which) & caught one in each hand, when lo & behold I saw a sacred Panagæus crux major; I could not bear to give up either of my Carabi, & to lose Panagæus was out of the question, so that in despair I gently seized one of the carabi between my teeth, when to my unspeakable disgust & pain the little inconsiderate beast squirted his acid down my throat & I lost both Carabi & Panagæus!8

I was quite astonished to hear of a terrestrial Planaria; for a year or two ago I described in the Annals of N. H. several beautifully coloured terrestrial species of the S. hemisphere, & thought it quite a new fact.9 By the way you speak of a sheep with a broken leg not having flukes: I have heard my Father aver that a fever or any serious accident, as broken limb will cause in a man all the intestinal worms to be evacuated; might not this possibly have been the case with the flukes in their early state.10

I hope you were none the worse for Southampton; I wish I had seen you looking rather fatter: I enjoyed my week extremely & it did me good. I missed you the few last days & we never managed to see much of each other; but there were so many people there, that I for one hardly saw anything of any one.—

Once again thank you very cordially for your kind present & the pleasure it has given me, & believe me | Ever most truly yours | C. Darwin

I have quite forgotten to say how greatly interested I was with your discussion on the statistics of animals: when will Nat: Hist: be so perfect that such points, as you discuss, will be perfectly known about any one animal!11

1
Jenyns 1846. See letter to Leonard Jenyns, [14 or 21 August 1846]. There is an annotated copy in the Darwin Library–CUL.
2
Jenyns 1837. On the copy of this letter he made for Francis Darwin (DAR 145), Jenyns noted: ‘Darwin has here made a mistake: the paper to which he alludes was published in the first Number of the ‘Magazine of Zoology and Botany.’ 1837.’ The confusion undoubtedly arose because the Magazine of Zoology and Botany changed its name to Annals of Natural History in 1838. Jenyns’ paper, dated 21 April 1836, appeared in the volume for 1838. It was entitled ‘Some remarks on the study of zoology, and on the present state of the science’.
3
Jenyns noted on the copy of this letter (DAR 145) that, ‘These subjects were subsequently treated of in a separate volume ‘Observations in Meteorology.’ 1858.’ See Jenyns 1858.
4
Constantin Wilhelm Lambert Gloger. CD’s annotated copy of Gloger 1833 is in the Darwin Library–CUL.
5
Brehm 1831.
6
Jenyns 1837, pp. 23–6, discusses the problem of determining highly variable species, citing both Brehm 1831 and Gloger 1833.
7
Jenyns (1846, pp. 161–2) described young martins daubing mud on house walls with no apparent intention of building a nest; he interpreted the behaviour as an instinct showing itself ‘before it is wanted’.
8
Jenyns mentioned a similar incident (Jenyns 1846, pp. 234–5). For CD’s recollections of Panagaeus crux major see Autobiography, p. 62. Cychrus rostratus is a synonym of C. caraboides subsp. caraboides, the long-headed carabus.
9
‘Brief descriptions of several terrestrial Planariae’, Collected papers 1: 182–93.
10
A phenomenon previously mentioned in letter to Henry Denny, 3 June [1844].
11
Jenyns 1846, pp. 331–65, followed by a ‘Calendar of periodic phenomena in natural history, as observed in the neighbourhood of Swaffham Bulbeck’, pp. 366–412.

Manuscript Alterations and Comments

1.6 this] over ‘I’
3.4 splitting] above del ‘cracking’
3.5 spherical] interl
3.5 maggot] altered from ‘maggots’
3.8 two] after del ‘some’
3.13 his acid] interl
3.13 Carabi] over illeg
4.6 possibly] interl

Please cite as “DCP-LETT-1009,” in Ɛpsilon: The Charles Darwin Collection accessed on 5 June 2025, https://epsilon.ac.uk/view/dcp-data/letters/DCP-LETT-1009