During the short time which has elapsed since Harvesting Ants and Trap-door Spiders left the printer's hands, fresh material has rapidly accumulated, and an assiduous search after these creatures, and the continued study of their works and ways, has met with ample reward and encouragement.
It was my wish, when originally publishing these observations, many of which were due to the active co-operation of friends, to invite my readers to take part with me in my pleasure and pursuits, so that we should from that time work together, and, by communicating our discoveries to each other, increase our knowledge, and at the same time enlarge the field of our research. My intention was that we should leave to others the necessary work of collection, preservation, and arrangement, and that, while our fellow naturalists pin specimens into classified cabinets, and devote long hours to the description of peculiarities of form and colour, we should undertake the lighter task of complementing their labours by observing and recording the habits and conditions of existence of the creatures themselves.
Looked at in this light, the present pages and those of the preceding work may be regarded as so many drawers in our Cabinet of Habits, and though, as we open drawer after drawer, many gaps and blank spaces remind us how much remains to be done in order to complete the collection, yet the interest and suggestiveness of the specimen-facts already secured, should encourage and direct us onwards. There have not been wanting instances in which my readers have associated themselves with me in the way indicated, and it is with pleasure, when reviewing the entire work, that I recall how many of its most interesting features are due to the researches and assistance of friends,[109] and commemorate at once their discoveries and unfailing kindness. I had certainly expected that before this time some new species of harvesting ants would have been discovered, either on the Riviera, where attention has been especially called to the subject, or in other parts of Europe, where dissimilar conditions might have been expected to be associated with a different fauna; but this has hitherto not been the case.
[109] To all who have rendered me this valuable help I tender my cordial thanks. I am under very special obligations to Mr. Pickard-Cambridge, for descriptions of spiders, and to Mr. F. Smith for the names of the Ants; assistance which I should have found it almost impossible to dispense with or to replace.
One might naturally suppose that if harvesting ants were discovered in localities very widely distant from each other, they would prove to belong to different species, but thus far, both in Europe and Northern Africa, it is the same two well-known species of Atta barbara and A. structor that constantly reappear.
For instance, I have recently learned that harvesting ants are found at Cadenabbia on the lake of Como, and at Montpellier in Southern France; but on examination, the ants from the former place are clearly seen to belong to the species structor, and those from Montpellier to the two species structor and barbara.
I was greatly interested to receive specimens of ants, and of the seeds which they were carrying and storing beneath the stones of a paved road at Cadenabbia, for this is the northernmost point[110] at which the habit of harvesting has as yet been noted. This discovery suggests the possibility of the occurrence of the habit in the warmer and more sheltered of the Swiss valleys. When at Montpellier in May last I frequently observed long trains of ants bringing seeds and small dry fruits to their nests, but these harvesters also turned out on close inspection to be Atta structor and A. barbara, with its red-headed variety. These, it will be remembered, are the only species of European ants which have as yet been proved to be harvesters and seed-storers in the fullest sense of the term, that is to say, which not only gather and carry seeds, but also store them in large quantities below the surface of the ground.[111]
[110] I have related in a note at the foot of p. 4 in Ants and Spiders how Formica nigra in England, though paying no attention to seeds generally, will sometimes collect the fresh seeds of the sweet violet (Viola odorata).
When I published this account I was quite unaware that the fact that certain English ants collect sweet violet seeds had been observed by Mr. R. Wakefield forty years before.
This was communicated by Mr. Wakefield in a letter to Mr. John Curtis, the substance of which was read before the Linnean Society in 1854, and published in their Proceedings (see Proceedings of the Linnean Society, ii. 293), where we read: "He (Mr. Wakefield) states that he has seen the black species (Formica nigra, L.) for days and nights together industriously occupied in dragging to its cells the seeds of the common violet (Viola odorata, L.)