Abstract
THE part of the Archives Néerlandaises, published by the Societé Hollandaise des Sciences à Harlem, for 1870, contains the results of some very interesting experiments undertaken by M. H. Weijenbergh, jun., on the above subject, one fraught with considerable interest to others besides entomologists. By Parthenogensis is meant the power that is possessed by females of producing eggs endowed with vitality, and from which young ones are produced, without impregnation taking place on each occasion. This subject has been extensively treated by von Siebold in his “Wahre Parthenogenesis bei der Schmetterlinge und Bienen,”Leipzig, 1856, but confirmatory and new investigations were much needed. Those of M. Weijenbergh were conducted with every possible care and precaution, so that they can be relied upon. In the autumn of 1866 he saw a male and female of the species Liparis dispar together, and some days afterwards he saw in the same place a great quantity of the eggs, about 500 in number. In order to leave the rearing of these to natural processes, as far as possible, he left them exposed all the winter in the open air, and in April 1867, he removed them into his house. Before the end of the month the caterpillars had successively made their appearance. These were regularly fed, and by the middle of July each of the chrysalides which had been formed during June gave birth to a perfect butterfly. It was easy, with a little practice, to distinguish the sexes whilst in the caterpillar state, and all the males were removed as far as possible, and the females were placed in a box closed to all access from without. So successfully was this separation of the sexes effected, that only one male butterfly made its appearance among the females; and, as these had been successively removed to a third closed box as soon as they escaped from the chrysalis state, it was only necessary to sacrifice the three or four females which were in the box at the time. In all, about sixty females were obtained, to which there was absolute certainty that no male could by any possible chance have had access. Of these, two-thirds laid eggs in the autumn,—some, one, two, or three eggs only; others as many as ten or twenty, but yet even at the most not one-twentieth of the eggs of their mother. The other one-third laid no eggs at all In all about 400 eggs were collected, which were removed and carefully packed up till April 1868, when a large number of little caterpillars were seen. These were immediately placed on leaves in a large glass vase and watched carefully. It was easily to be seen that this batch of caterpillars possessed far less vitality than those of the previous year. A large number of the eggs dried up and were worthless, some fifty caterpillars alone appearing, and of these only about forty survived to become chrysalides. From these, by the end of July, twenty-seven butterflies made their appearance. The same precautions having been taken as before, the number of females was found to be fourteen. Of these, when again there had been no possibility of male access, one half laid no eggs, the remaining half, however, laying in all a fair number. As in previous years, these were removed and left all the winter carefully packed up, till, in April 1869, three years after the commencement of the I experiments, young caterpillars again made their appearance. From these, strange to say, the number of butterflies obtained was in excess of those obtained in the previous year. The number of females as compared with males, was almost the same, in contradiction to the results of other investigators, which had indicated the probability of the ratio of the males to the females greatly increasing with each additional year. The eggs laid by the females of this year, carefully isolated as before, were packed up during the winter, but when examined in the spring of last year, 1870, no caterpillars made their appearance, the eggs became shrivelled up, and the experiment was at an end. There is every reason to believe that it was most carefully conducted, and that every regard was paid to strict accuracy during the whole three years or more that the experiment was being carried on. The results amount to these:—
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E., J. Parthenogenesis Among the Lepidoptera . Nature 5, 149–150 (1871). https://doi.org/10.1038/005149a0
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DOI: https://doi.org/10.1038/005149a0