196 Johnson. — On the Nursing of the Embryo 
objective, and even under an inch objective, can, in favourable 
examples, be traced more or less clearly (Fig. 16). 
Elongation of the Embryo-sac in other Parasites. 
There are many examples of an elongation of the embryo- 
sac at its antipodal end, 3 as well as some of an elongation at 
its synergidal end, 1 2 in the Loranthaceae. My impression, from 
an examination of the more recent publications on parasitic 
Phanerogams , was that, though it was usual, in the very closely 
allied order Santalaceae , for the apex of the sac to grow out 
from the ovule upwards and forwards into the ovarian cavity 
towards the descending pollen-tube, there was no example of 
a backward prolongation of the sac. It seemed to be a useful 
investigation to search for the existence of such a backward 
growth, the descriptions and illustrations of Myzodendron in 
Flora Antarctica suggesting this genus as a very suitable one 
for the purpose. It was not until the examination was finished 
that I found my impression was an erroneous one. In a report 3 
by Mirbel, Brongniart, and Jussieu on a paper read by J. 
Decaisne in 1839, before the Academy of Science of the French 
Institute, the full title of the paper being ‘ Observations sur 
le developpement du pollen dans le Gui, sur les changements 
que presentent ses ovules et ceux du Thesium,’ the following 
paragraph occurs, ‘ M. Decaisne a decouvert, dans ce meme 
appareil ovulifere du Thesium, un autre organe, dont il est 
difficile de bien determiner l’analogue dans tout ce que etait 
connu jusqu’ici. C’est un tube situe longitudinalement, dans 
1’epaisseur de la colonne centrale, digite inferieurement, simple 
et renfle a son extremite superieure qui perce la colonne et 
vient s’appliquer sur un point du sac embryonnaire. C’est 
au moment de la fecondation, 011 le sac embryon- 
naire rompt le nucelle, quapparait ce tube interieur, et qu’il 
perce de son cote le tissu environnant, pour se mettre en rap- 
port avec le sac.’ After a reference to Griffith’s discovery of 
1 Loranthus and Viscum. 2 Same genera. 
3 Ann. d. Sc. Nat. ser. 2, tome xiii, p. 300, PI. ii, Figs. 12-14. 
