The nest of Formica cinerea, captured at the same time, produced four larvæ, all of which perished before arriving at the pupa stage. The larvæ of males and of queens are much larger than those of workers, and these larvæ were too big to have been those of workers. In a nest of Formica fusca, which I have had under observation since August 1876, three pupa were produced. They were all males. Another nest of Formica fusca produced a single young one, which also was a male. Lastly, my nest of Polyergus rufescens, which M. Forel was so good as to send me in the spring of 1876, in 1879 produced twelve pupæ. Eleven of these turned out to be males. The other one I lost; and I have little doubt that it was brought out and thrown away. It was certainly not a worker. As regards the first three of these pupa, I omitted to record at the time whether they belonged to the Polyergus or to the slaves, though I have little doubt that they belonged to the former species. The last eight, at any rate, were males of Polyergus. Indeed, in all of my queenless nests, males have been produced; and in not a single queenless nest has a worker laid eggs which have produced a female, either a queen or a worker. Perhaps I ought to add that workers are abundantly produced in those of my nests which possess a queen. While great numbers of workers and males have come to maturity in my nests, with one exception not a single queen has been produced. This was in a nest of Formica fusca, in which five queens came to maturity. The nest (which, I need hardly say, possessed a queen) had been under observation since April 1879, and the eggs therefore must have been laid in captivity. The nest had been richly supplied with animal food, which may possibly account for the fact. It is known that bees, by difference of food, &c., possess the power of obtaining at will from the same eggs either queens or ordinary workers. Mr. Dewitz,1 however, is of opinion that among ants, on the contrary, the queens and workers are produced from different kinds of eggs. He remarks that it is very difficult to understand how the instinct, if it is to be called instinct, which would enable the working ants to make this difference can have arisen. This is no doubt true; but it seems to me quite as difficult to understand how the queens, which must have originally laid only queen eggs and male eggs, can have come to produce another class. Moreover, however great the difficulty may be to understand how the ants can have learnt to produce queens and workers from one kind of egg, the same difficulty exists almost to the same extent in bees, which, as Mr. Dewitz admits, do possess the power. Moreover, it seems to me very unlikely that the result is produced in one way in the case of 1 Zeit. für wiss. Zool. 1878, p. 101. bees, and in another in that of ants. It is also a strong argument that in none of my nests, though thousands of workers and males have been produced, had I ever observed a queen to be so until the year 1879. On the whole, then, though I differ from so excellent a naturalist with much hesitation, I cannot but think that ants, like bees, possess the power of developing a given egg into either a queen or a worker. I have already mentioned that the previous views as to the duration of life of ants turn out to be quite erroneous. It was the general opinion that they lived for a single year. I have, however, now in my possession two queens, which I have had under observation ever since the year 1874. They must now (August 1882) therefore be more than eight years old. They seem in perfect health, and in 1881 laid fertile eggs, a fact which suggests physiological conclusions of great interest. I have, moreover, little doubt that some of the workers now in this nest were among those originally captured, the mortality after the first few weeks having been but small. This, however, I cannot prove. A nest of F. sanguinea, which M. Forel kindly forwarded to me on September 12, 1875 (but which contained no queen), gradually diminished in numbers, until in February 1879 it was reduced to two F. sanguineas and one slave. The latter died in February 1880. One of the two mistresses died between May 10 and May 16, 1880, and the other only survived her a few days, dying between the 16th and 20th. These two ants, therefore, must have been five years old at least. It is certainly curious that they should, after living so long, have died within ten days of one another. There was nothing, as far as I could see, in the state of the nest or the weather to account for this, and they were well supplied with food; yet I hardly venture to suggest that the survivor pined away for the loss of her companion. Some workers of F. cinerea lived in one of my nests from November 1875 to July 1881. In a nest of F. fusca, which I brought in on June 6, 1875, and in one of Lasius niger brought in on July 25, 1875, there were no queens; and, as already mentioned, no workers have been produced. Those now living (August 1882) are therefore the original ones, and they must be more than seven years old. The duration of life in ants is therefore much greater than has been hitherto supposed. Though I lose many ants from accidents, especially in summer, in winter there are very few deaths. I have given the following figure (fig. 2), which represents a typical nest belonging to Lasius niger, because it is a good instance of the mode in which my ants excavated chambers and galleries for themselves, and seems to show some ideas of strategy. The nest is, as usual, between two plates of glass, the outer border is a framework of wood, and the shaded part |