Has read a paper, presumably by JDH, using the Madeiran flora to argue against Forbes’s doctrine.

JDH asked how far CD will go in attributing common descent; he intends to show "the facts & arguments for & against the common descent of species of same genus; & then show how far the same arguments tell for or against forms, more & more widely different".

Congratulations to JL on finding musk-ox fossil.

Discusses how best to simulate the light at a particular point on the earth’s surface using coloured glass; considers sunlight as composed of three "principles", varying in proportion according to latitude, which affect germination, lignification, and floriation.

Parcels sent to Down by coach may get lost.

Thanks JSH for all he has done. His botanical little girls are marvellous. His marking of the list of dubious species is what CD wanted. Explains that he wanted to ascertain whether closely allied forms belong to large or small genera.

Invites JSH to dine at CD’s brother’s house in London.

Informs CD which colours of glass accelerate germination, lignification, and floriation; advises CD on obtaining such glass and offers his help in any experiments.

Praise for JDH’s Flora Indica [J. D. Hooker and T. Thomson (1855)] from CD and C. J. F. Bunbury.

CD and J. S. Henslow dining in London. JDH invited.

Delighted JSH can dine. Has invited Hooker.

Thanks him for Lychnis seed.

Asks for umbel of wild celery. Wants to ascertain whether wild or tame plants produce most seed.

Burying charlock seeds.

Morning with H. C. Watson; discussed problems of inferences from buried seeds.

Gives names of German dealers who provide seed of superior quality.

When JDH goes to Germany, will he ask seed men if their marvellous true breeding lines are the result of selection.

Seeds of two tropical island plants have floated for ten days.

Sends a catalogue of plants [missing] with the close species marked.

Close species in large and small genera.

Artificiality of botanical classification.

Asks JSH to identify an umbellifer.

Describes his efforts to compare number of seeds of wild and cultivated plants.

Asks that more wild celery be collected and seeds counted. Seeks to verify whether "most typical form produces most seed" and whether cultivation lessens fertility.

On geographical distribution of plants. Plant systematics and natural classification.

Forwards two specimens of beans found on north coast of Norway.

Expresses his general opinion on the relative closeness of species in large and small genera. Warns that the size of a genus is dependent upon the locality and extent of the flora studied, that definitions of close species are not consistent, and that peculiarities of botanical classification will influence any attempt to assess the comparative closeness of species in different genera.