Dr. Filippi on the Generation of an Hymenopterous Insect. 461 



Fig. 6. Vertical section of the prothalliura and upper part of the large spore 

 of Selaginella denticulata, showing the embryo developed from the 

 central cell of one of the archegonia, carried down by the growth 

 of its suspensor, so as to be imbedded in the cellular tissue filling 

 the upper pai-t of the cavity of the spore. {Hofmeister .) 



Fig. 7- Young embryo of iS. denticulatahreokm^ through the prothalhum, 

 its bud now outside the spore. {Hofmeister.) 



Fig. 8. Small spore of Selaginella helvetica bursting and discharging cel- 

 lules containing spermatozoids. {Hofmeister.) 



E. Phanerogamia Gymnospermia. 



Fig. 1. Vertical section of an ovule oi Pinus austriaca, from a cone just 

 flowered : a, nucleus ; b, embiyo-sac. 



Fig. 2. Vertical section of the ovule of Pinus sylvestris in May of the second 

 year: b, embryo-sac filled with cellular tissue; c, pollen-tubes 

 penetrating the nucleus. 



Fig. 3. Portion of the embryo-sac and upper part of the nucleus of Pinus 

 Strobus: b, embryo-sac; c, pollen traversing the tissue of the 

 nucleus (a) ; d, corpuscles. 



Fig. 4. Vertical section of a corpuscle of Abies excelsa just ripe for impreg- 

 nation : b, tissue filling the embryo-sac ; d, free cells in the cavity 

 of the corpuscle ; e, the four cells between which the intercellular 

 canal passes. 



Fig. 5. Vertical section of a corpuscle of Pinus Strobus, to which the pol- 

 len-tube (c) has just arrived ; d, free cells swimming in the con- 

 tents ; /, embryonal vesicle. 



Figs. 6-10. Progressive stages of development of the suspensors of Pinus 

 Strobus. 



Fig. 11. The suspensor just before separating. 



Fig. 12. The same, detached below. 



Fig. 13. A suspensor (three being cut away), somewhat further advanced, 

 with the rudimentary embryo {g) at the base. 

 (All from Hofmeister.) 



F. Phanerogamia Angiospermia. 

 Fig. 1 . Ovule of Orchis Morio just impregnated (original). 

 Figs. 2-5. Successive stages of development of the embryo. 

 Fig. 6. Embryo with the suspensor-like filament which grows up out of 



the inicropyle (original). 

 F^g. /. Embryo-sac of Veronica triphyllos : a, pollen-tube ; b, suspensor. 



{Tulasne.) 

 Fig. 8. More advanced : c, endosperm-cells ; c?, embryo. (Tulasne.) 

 Fig. 9. More advanced embryo extracted. {Tulasne.) 



XXXVII. — Upon the Mode of Generation of an Hymenopterous 

 Insect of the Family of the Pteromalidse. By Dr. Ph. de 

 Filippi, Professor of Zoology at Turin. 



[With a Plate.] 



I HAD collected during the month of May 1851, from the 

 vineyards near Turin, a quantity of leaves rolled up by the 

 Rhynchites Betuleti, in order to study the development of the 

 embryo in the very transparent ova, which this little Coleopterous 

 insect lays in them. What was my sui-prise, however, when I saw 



