266 Linnean Society. [Dec. 20, 



a notice of which is given in the ' Annals of Natural History ' for 

 June of the same year. In this paper Prof, de Filippi gives a very 

 singular and interesting account of the mode of reproduction of a 

 Hymenopterous insect, probably a species of Pteromalus, whose 

 business it appears to be to keep down the multiplication of Attelabus 

 Betuleti. He believes that the facts observed by him in regard to 

 this parasite are strictly analogous to those described as occurring in 

 DistomcB, which (according to the well-known observations of Siebold 

 and Steenstrup) do not directly generate other Distomce, but larvae 

 which generate other larvae, and then CercaricB, which being them- 

 selves the proper larvae of Distomce are transformed into them. In 

 like manner the Pteromaline insect of the Attelabus (and perhaps 

 other parasitic insects) does not generate its progeny directly, but 

 intermediate beings which are the mothers of this progeny, and 

 which have received from Steenstrup the name of Nurses. This 

 parasite then presents us, according to Prof, de Filippi, with a case 

 of alternation of generations, the first example known in the class of 

 Insects. Mr. Curtis, however, is of opinion that the case is rather 

 one in which a second parasite deposits its ovum in the interior of 

 the first while yet in the larva state, and thus prevents the too rapid 

 increase of the first parasite, which might otherwise multiply so 

 greatly as to exterminate the weevil itself. When and how the 

 eggs of the second parasite are introduced into the first Mr. Curtis 

 regards as a curious question, and well worthy of investigation on 

 account of the physiological interest attached to the subject. He 

 concludes by some remarks on the great importance of a knowledge 

 of the oeconomy of parasitic insects, by whose agency other noxious 

 and larger species are rendered much less destructive than they might 

 otherwise become ; and of the diflfusion of this knowledge, especially 

 among the cultivators of the soil, lest (as is too often the case) they 

 should be led to destroy the very creatures through whose means we 

 are frequently protected, if not from absolute famine, at least from a 

 scarcity of the most necessary productions of the earth. 



Read also " Remarks on the so-called Eye-spot of the Infusoria 

 and Microscopic Alges." By Arthur Henfrey, Esq., F.R.S., F.L.S. &c. 



Mr. Henfrey states, that in the course of an extensive series of 

 observations on the microscopic Algae, especially in investigations of 

 the effect of reagents upon the tissues and contents of the cells, he 

 has frequently been completely baffled by the uncertainty which 

 presented itself as to the real existence of colours exhibited by 

 objects. The decomposition of light taking place in these minute 



