Several of your correspondents have noticed the scarcity of Holly-berries in different parts of the country, and the same thing may be observed to a remarkable extent in this neighbourhood.² Your correspondents account for the fact by spring frosts, but it must be remembered how hardy a plant the Holly is, being found in Norway as far north as the 62d degree of north latitude (Lecoq Géographie Botanique, vii., p. 370),³ another explanation seems to me more probable. Bees of all kinds were in this neighbourhood extraordinarily rare during the spring. I can state this positively, as I wished to observe a particular point in their behavior in sucking the common red Clover; and, therefore, often visited the fields where the plant was growing; but I could see very few bees. I was so much struck by this fact that I examined several meadows abounding with flowers of all kinds, but bees were everywhere rare. Reflecting, in the course of the summer, on this extraordinary scarcity, it occurred to me that this part of England would be temporarily in the same predicament as New Zealand before the introduction of hive bees, when the Clovers (which, as I know by trial, require the aid of bees for perfect fertilisation) would not set seed.⁴ By an odd chance I received the very next morning a letter from a stranger in Kent, asking me if I could assign any reason for the seed-crop of Clover having largely failed in his neighbourhood, though the plants looked vigorous and healthy.⁵ Now the Holly is a diœcious plant, and during the last forty years I have looked at many flowers in different districts, and have never found an hermaphrodite. Bees are chief transporters of pollen from the male to the female tree, and the latter will produce but few berries if bees are scarce. In my Origin of Species I state that, having found a female tree exactly 60 yards from a male tree, I put the stigmas of twenty flowers, taken from different branches, under the microscope, and on all, without exception, there were a few pollen-grains, and on some a profusion. As the wind had set for several days from the female to the male tree, the pollen could not thus have been carried. The weather had been cold and boisterous, and therefore not favourable; nevertheless every female flower which I examined had been effectually fertilised by the bees, which I saw at work, and which had flown from tree to tree in search of nectar.⁶ Therefore, as I believe, we cannot decorate our Christmas hearths with the scarlet berries of the Holly, because bees were rare during the spring; but what caused their rarity I do not in the least know.

Charles Darwin, Down, Beckenham, Kent, Jan. 3.