From G. R. Waterhouse 17 April 1858
April 17. 1858
My dear Darwin
Having been “drawn out” at the last meeting of the Entomological Society on the subject B’s cells, I was called upon by the Secretary to furnish some notes of what I said, in order that it might be inserted in the minutes—1 I of course made the notes as short as possible & to do so, confined myself almost entirely to the theoretical part of the matter—indeed I felt obliged to keep as near as possible to what I really did say— I happened to have used the word “accidental” in con-nexion with the hexagonal form of cell, and as that was one of about 6 words which I had said, somebody got up & begged I would explain what I meant by using that term. so came a short explanation— after the Secretary has copied out my notes into the minute book I will get them back again & send them to you.
You say that the case of the Icaria bothers you,2 furnishing a considerable difficulty, & I must say I was much surprised at it, but after all, the cell with the free angular sides is in contact with other cells in one part of its circumference, and this circumstance it appears to me furnishes a key to the difficulty, especially when we call to our remembrance the way in which the new cells are added to the edge of the comb—always in the interstices of two cells—the first atom of material that is laid down to commence a cell is stuck in the entering angle— Theoretically speaking I say that the cells of the wasp are cylinders altered into hexagons as they proceed—excepting, (generally) the case of the outermost tier, and that tier we must bear in mind is close up to the side of the nest—
I think I might safely have said always instead of generally, if I had defined the outermost tier of cells in the comb as that tier which is so near to the side of the nest as not to admit of work being carried on beyond it— The exceptional cases, it appears to me almost certain, occur only where there is a little more space than usual owing to irregularities in the outline of the nest—here the cells are altered into the hexagonal form, altho’ other cells are not formed externally to them, so that in fighting for mere words, it might be objected to my theory,—that the contact with other cells is not a necessary condition to produce angular cells— I am ready to fight this point out— I ought here to say that if the word “not” is left out in the above underlined sentence, that sentence gives the pith & marrow of my theory—
Fearing that I should have to make so many alterations in the part that follows, that you would scarcely be able to read it I took a separate sheet of paper to clear my ideas upon—it is, however, I hope legible so I send it—
Faithfully yours | Geo. R. Waterhouse
Now to come to the Cells of the Icaria— Wasps build hexagonal cells because they carry up a number of cells almost simultaneously working at the inner, and the outer side of each cell alternately— (The bottom of the cell of the wasp does not come in contact with other cells, and is not angular, but the outer surface is hemispherical, & thus differs from the cell of the Hive bee, which is in contact with other cells, and is angular, and is composed usually of three rhomboidal plates, but sometimes has one plate, sometimes four)
The outermost cells of the comb formed by the wasp usually are flat sided only when the come in contact with the cells of the preceeding tier—but sometimes some of the outermost tier of cells are hexagonal presenting two free, flat sides as in cell C of the Icaria— Now as the foundations of new cells are laid in the interstices of the old, I suppose it is likely that the alteration of the circular outline commences first at the entering angles left by the two adjoining cells—(the angles a, a) & proceeds towards the salient angle b— In some cases the Wasp’s outermost cells have three, free flat sides, as in the cell B of the nest of Icaria—in which case I suppose the insect proceeded as before working outwards from the entering angles a a towards the angles b. b., and that subsequently the superfluous material is removed from the side c— Lastly, in the cells of the Icaria we have an instance of a cell (A) with four free, flat sides— I have never seen such a cell in the nest of the Wasp or Hornet, but it might be produced by the insect’s working as before described commencing at the angles a a and continuing on either side from b b, towards c— If this were the case then the fact that the cell A is in contact with two other cells B & C would have influenced the hexagonal form of the cell A — And now, for one moment, consider the amount of proability which is given to this view, by the number of facts which I have pointed out to you, and especially by the conditions presented by the nests of allied insects which are placed by the side of the nest of the Icaria—one of which is composed of free cylindrical cells— I do not pretend to say that the explanation is the correct one, but I wish to show that with my theory in view it is not an impossible case to find a cell with 4 free sides— A cell with six free sides has not yet been found, & I have looked pretty sharply after cells in general during this last 20 years—4 [DIAGRAM HERE] Icaria [double underlined] c b a b B a b A C c b a b a
Bees’ cells; GRW thinks hexagonal shape is accidental. Encloses notes on cells of Icaria.