504 TEXT-BOOK OF ENTOMOLOGY 



egg-calyx (Fig. 478, c), in which the ripe eggs collect before passing 

 into the oviduct (ov). 



As the result of his investigations on the origin of the cellular elements of the 

 ovaries of insects Korschelt concludes : 



1. The different cell-elements of the egg-tubes, eggs, nutritive cells, and 

 epithelium arise from identical undifferentiated elements situated in the contents 

 of the earliest_germ of the egg-tubes. 



2. The first formation of the cellular elements present, and the differentiation 

 of the individual compartments of the egg-tube, occur during embryonic and 

 larval life. 



3. The undifferentiated elements of the terminal chamber correspond to the 

 embryonic condition, while in post-embryonic time, and even during imaginal 

 life, a new formation of the different kinds of cells takes place. 



4. The mode of origin of the different kinds of cells from the undifferentiated 

 elements varies greatly in different insects. 



5. From their histological nature, and from the mode of origin of their 

 elements, the most complex egg-tubes and those provided with nutritive 

 compartments are phylogenetically derived from those without such nutritive 

 compartments. 



6. The nutritive cells in certain cases originate in the same way and at the 

 same time as the germ-cells, and are therefore to be regarded as germ-cells 

 which have abandoned the function of egg-making, and exchanged it for the 

 production of nutritive material. 



7. In the egg-tubes with numerous nutritive compartments the nutritive cells 

 can originate at the same place as the egg-cells, and they afterwards still lie 

 intermingled with these in the beginning or upper part of the egg-tubes. 



8. While the capability of egg-making of the germ-cells originally situated in 

 the extremity of the terminal chamber gradually becomes transferred to those 

 at the base of the terminal chamber, and the first transform into nutritive cells, 

 egg-tubes with nutritive compartments at the base may be found. 



9. The nutritive cells of certain forms arise independently of the germ-cells 

 and therefore could not have previously originated from them. 



10. The epithelium has in all forms nearly the same mode of formation ; it 

 everywhere shows a close similarity to the undifferentiated elements of the 

 terminal chamber, out of which it directly develops. As to the fact of forma- 

 tion of epithelium through the germ-vesicles (Keimblaschen), nutritive-cell 

 nuclei, or the so-called "ooblasts," I could not feel certain. 



11. Neither the eggs of Hemiptera or of other insects arise through the 

 agency of "ooblasts," but like the epithelial and nutritive cells arise by a 

 gradual differentiation from the indifferent elements of the ovarian tubes. 



12. The different elements of the egg-tubes, also the eggs, have the morpho- 

 logical value of cells. 



Origin of incipient eggs in the germ of the testes. Heymons has detected in 

 the germ of the testes of the male larvae of Phyllodromia germanica 1 mm. in 

 length, young or incipient eggs, similar to those seen in the ovarian tubes of 

 the female larva of the same size. In another male larva of the same size also 

 occurred short cylindrical tubes each with a terminal thread, which had the 

 appearance of rudimentary egg-tubes. Hence he thinks that every part of the 

 genital germs (Anlagen) in the male, which are not concerned in the formation 

 of testicular follicles, represents the germ of a female genital gland. As is well 

 known, no insects are hermaphroditic, but this case of the practical origin of 

 eggs and egg-tubes in the lowest division of the male efferent passage, which is 



