106 M. Balbiani on the Reproduction 
IODINE. 
Dr. Nylander says (/. c.), “ D. Fries affert me reactionem iodo 
effectam attulisse tanquam signum Lichenes omnino a Fungis 
distinguens, etsieam nunquam aliter eo respectu proposui quam 
sicut adminiculum accedens in certis casibus, ubi dubium re- 
stitit in formis Lichenaceis infimis a Fungis simillimis distin- 
guendis.” 
XVIII.—On the Reproduction and Embryogeny of the Aphides. 
(Third Note.) By M. Baxsrani*. 
Havine described in my two previous communications the phe- 
nomena presented by the viviparous Aphides in their reproduc- 
tion and development, I now come to the examination of the 
same facts in the oviparous Aphides, which represent the last 
generation produced by the preceding individuals towards the 
close of the year. This autumnal generation consists, as is well 
known, of males and females, which copulate, when the females 
lay eggs which pass through the winter and are hatched only in 
the following spring. 
The oviparous Aphides are produced under conditions exactly 
similar to those which governed the development of the vivi- 
parous forms. Not only does the embryo originate in an ovule 
differing in no respect from that producing the latter, but all 
that I have said with regard to the first modifications of the 
ovum, the formation of the blastoderm and embryos, and the 
production of the male and female generative elements is per- 
fectly applicable to them. From this it results that these ani- 
mals, which, after their birth, will give the most manifest signs 
of the separation of the sexes, appear during a great part of 
their embryonic existence lke truly hermaphrodite creatures, 
which it would be impossible to distinguish from their oviparous 
[?viviparous] congeners. It is only when their development 
has become considerably advanced that the first tendency to the 
separation of the sexes is manifested. How this separation is 
brought about, is what we shall now proceed to examine. 
Of all the means at the command of nature for the attainment 
of this end, the most simple would evidently be to affect with 
atrophy one of the sexual apparatus, the other continuing its 
normal development. But this is not what takes place. The 
male apparatus does not disappear, and is found, after birth, in 
individuals of both sexes, with characters scarcely differing from 
* Translated from the ‘Comptes Rendus,’ June 25th, 1866, pp. 1390- 
1594. See Annals, ser. 3. vol. xviil. pp. 62-69. 
