PARTHENOGENESIS OR AGAMOGENESIS IN LEPIDOPTERA.. 25 



mori (Comptes Renins Hebdomadaires des Seances de V ' Academie des 

 Sciences, Paris, liii., 1861, pp. 1093-1096), where he remarks that it 

 has long been customary, in the silk-producing countries of France, to 

 regenerate a worn-out race by using " la graine vierge," i.e., eggs pro- 

 duced from females that have not been paired with males. He details 

 certain experiments made in 1851, which show the proportion of 

 female moths that give fertile eggs parthenogenetically. From these 

 experiments we learn that he had 300 yellow Milanese cocoons of a 

 form of B. mori, that gives only one generation per year. The results 

 work out as follows : — June, 1851 — 300 cocoons selected, each cocoon 

 placed in a small cardboard box covered with gauze, so as to com- 

 pletely imprison the moth on emergence. The 300 cocoons produced 

 147 females and 151 males. The boxes containing males were re- 

 moved and the females carefully preserved without being uncovered. 

 Of the 147 females, six gave fertile eggs. Two gave 7 eggs each, two 

 others 4 eggs each, one gave 5 eggs, and one 2 eggs. These 29 eggs, 

 preserved in their respective boxes without being uncovered, to render 

 error impossible, hatched May, 1852. Many other eggs, it is men- 

 tioned, passed from the pale yellow (colour when newly-laid) to the 

 slaty-grey hue, which replaces the former after some days in fertile 

 eggs. The summarised results of this experiment worked out at :— 

 147 females, laid about 58,000 eggs, of which 29 produced larvae, i.e., 

 about 1 : 2,000. 



Another experiment was made by Jourdan, in July, 1851, on white 

 cocoons from South China, of a form of B. mori, giving five or six 

 successive generations in one year. Fifty cocoons were separately 

 isolated, as in the last experiment. From these emerged 23 females 

 and 26 males. Seventeen of these females gave completely fertile 

 eggs. One gave 113, and the least productive 12. The total number 

 of eggs laid was 9,000, of which 520 produced larvae. This gives a 

 proportion of 1 : 17. They hatched seventeen days after being laid. 



Although these experiments proved conclusively that some virgin 

 females of B. mori could reproduce their kind without copulation, it was 

 evident from the results, that the parthenogenetic reproductive power 

 was exceedingly feeble. Of the two different races experimented upon, 

 that with five or six successive generations per year was much more 

 productive, parthenogenetically, than that with a single generation. 



One of the earliest essays on this subject was that of Von Siebold 

 (translated by Dallas), entitled: On a true parthenogenesis in moths and 

 bees. Siebold was led into his enquiries by some observations made 

 on the reproduction of a species of Psychid moth, which, he noticed, 

 propagated without copulation. He followed this up with observations 

 on bees and B. mori, and found that the phenomenon of reproduction 

 by virgin females was not at all uncommon. For this, he adopted the 

 term "parthenogenesis," which had previously been applied by Owen to 

 the phenomenon now known as " alternation of generations." 



According to Siebold, we learn that the oldest communication 

 relative to reproduction by female insects, sine concubitu, was made by 

 Albrecht of Hildesheim, who (in 1701) relates that he found a brown 

 pupa in a cocoon on a black-currant bush, and preserved it to see what 

 moth would emerge from it. At the end of July, a moth of yellowish- 

 white colour was disclosed, and in a few days laid a great number of 

 eggs, and then died. In April of the following year, Albrecht was 



