this reason
Darwin placed the plant among the tendril-bearers rather than among the
true leaf-climbers: see "Climbing Plants," Edition II., 1875, page 121.)
You looked at them here and agreed. But now the plant is old, what I
thought was a branch with two leaves and ending in a tendril looks
like a gigantic leaf with two compound leaflets, and the terminal part
converted into a tendril. For I see buds in the fork between supposed
branch and main stem. Pray look carefully--you know I am profoundly
ignorant--and save me from a horrid mistake.

LETTER 669. TO J.D. HOOKER.

(669/1. The following is interesting, as containing a foreshadowing of
the chemotaxis of antherozoids which was shown to exist by Pfeffer in
1881: see "Untersuchungen aus dem botanischen Institut zu Tubingen,"
Volume I., page 363. There are several papers by H.J. Carter on the
reproduction of the lower organisms in the "Annals and Magazine of
Natural History" between 1855 and 1865.)

Down, Sunday, 22nd, and Saturday, 28th [October, 1865].

I have been wading through the "Annals and Mag. of N. History." for last
ten years, and have been interested by several papers, chiefly, however,
translations; but none have interested me more than Carter's on lower
vegetables, infusoria, and protozoa. Is he as good a workman as he
appears? for if so he would deserve a Royal medal. I know it is not new;
but how wonderful his account of the spermatozoa of some dioecious alga
or conferva, swimming and finding the minute micropyle in a distinct
plant, and forcing its way in! Why, these zoospores must possess some
sort of organ of sense to guide their locomotive powers to the small
micropyle; and does not this necessarily imply something like a nervous
system, in the same way as complemental male cirripedes have organs of
sense and locomotion, and nothing else but a sack of spermatozoa?

LETTER 670. TO F. HILDEBRAND. May 16th, 1866.

Since writing to you before, I have read your admirable memoir on
Salvia (670/1. "Pringsheim's Jahrbucher," Volume IV., 1866.), and it has
interested me almost as much as when I first investigated the structure
of orchids. Your paper illustrates several points in my "Origin of
Species," especially the transition of organs. Knowing only two or three
species in the genus, I had often marvelled how one cell of the anther
could have been transformed into the moveable plate or spoon; and how
well you show the gradations. But I am surpris