can only come about in the course of a long series of generations'[14]. [14] _Aeussere Einflüsse als Entwickelungsreize_, Jena, 1894. [Illustration: FIG. 105. Ovary of a fertile Queen-Ant and ovaries of a Worker. _Od_, oviduct. _A_, one ovary of _Myrmica lævinodis_ with many ovarian-tubes, in each of which there is an almost ripe egg (_Ei_) and a younger egg (_Ei´_). _B_, the ovaries of a Worker of _Lasius fuliginosus_; each ovary has only one ovarian-tube, and no ripening egg-cells. After Elizabeth Bickford.] Against this proposition an observation by O. vom Rath has been cited. According to it, three drone larvæ which had been accidentally fed by the workers with royal food exhibited striking retrogressive peculiarities in their sexual organs. The testes contained only immature sperms (just before emergence from the pupa), and the copulatory organ was entirely wanting. That a certain degree of fatty degeneration of the testes should be caused by the 'unusual fattening' is not surprising, but it seems to me very questionable whether the absence of the copulatory organ can be referred to the abnormal diet; it ought to be definitely decided, by the investigation of numerous cases, whether some abnormal peculiarity in the constitution of the germ-plasm in these eggs was not the true cause. Hitherto, unfortunately, I have not been able to procure the fresh material necessary to decide this point[15]. From all this it must be evident that we are not justified in regarding either the absence of wings or the degeneration of the ovaries as a direct result of the inferior nourishment supplied to the workers in the larval state: but should any one still have doubt on this point I may mention that, among our indigenous ants, there are two species in which the workers are just as large as the fertile females, and that in tropical America a species (_Myrmecocystus megalocola_) occurs in which the workers are larger than the true females; this must mean that they have received more food than the females, though perhaps not the same mixture of food. [15] Since completing my manuscript I note that the point was settled three years ago, when Koshewnikow had the opportunity of investigating drone-pupæ which were abnormally reared in royal cells, and therefore fed with royal food. He found their sexual organs perfectly normal, and agrees with me that the abnormalities in Vom Rath's case must have been due to some other cause. (See the report by Von Adelung on the Russian paper in _Zool. Centralblatt_, Sept. 10, 1901.)