Search: Darwin, C. R. in correspondent 
Davidson, Thomas in correspondent 
1860-1869 in date 
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From:
Charles Robert Darwin
To:
Thomas Davidson
Date:
26 Apr 1861
Source of text:
DAR 143: 372
Summary:

Asks TD to carry out research on brachiopods to see whether the forms in one formation are intermediate between those above and below.

Describes unpublished study of spirifers by J. W. Salter.

Contributor:
Darwin Correspondence Project
From:
Charles Robert Darwin
To:
Thomas Davidson
Date:
30 Apr 1861
Source of text:
DAR 143: 373
Summary:

Thanks TD for his letter. Difficulties with CD’s theory are many and great, but CD thinks the reason is that we underestimate our ignorance. The imperfection of the geological record counts heavily for CD. His greatest trouble is weighing "the direct effects … of changed conditions of life without any selection, with the action of selection on mere accidental (so to speak) variability. I oscillate much on this head, but generally return to my belief that the direct [effects] … have not been great."

Is surprised that any one, like W. B. Carpenter, can go as far as to believe all birds may have descended from one parent, but will not go further and include all the members of the same great division. Such beliefs make "Divine mockeries" of morphology and embryology, the most important of all subjects.

Contributor:
Darwin Correspondence Project
From:
Thomas Davidson
To:
Charles Robert Darwin
Date:
3 May 1861
Source of text:
DAR 99: 1–2
Summary:

Sends three tables on the known geological distribution of genera and subgenera of Brachiopoda. Has been continually puzzled by intermediate forms, and is convinced that the greater number of species can be linked together. "Natura non facit saltum."

Contributor:
Darwin Correspondence Project
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