Dicotyledon—Caltha palustris . 
535 
EXPLANATION OF FIGURES IN PLATE XXX. 
Illustrating Miss Thomas’s paper on the Fertilization of Caltha. 
Abbreviations : n. of o., nucleus of the oosphere; s ., synergid ; g. n 1 ., first 
generative nucleus, that which fertilizes the oosphere : g. n 1 ., second generative 
nucleus, that which fertilizes the definitive nucleus; d. n. } definitive nucleus ; ant. } 
antipodal cell; p x and / 2 , polar nuclei. 
Fig. i. Young embryo-sac with polar nuclei in the first stage of fusion (p l and 
/)• x 450 - 
Fig. 2. Embryo-sac at the fertilization period. Nucleus of oosphere and first 
male generative nucleus, coalescing. The second generative nucleus is in a more 
advanced stage of fusion with the definitive nucleus. Antipodal cell displaced, 
x 245. 
Fig. 3. Definitive nucleus with second generative nucleus from Fig. 2, under 
greater magnification. This section includes but a thin slice of these nuclei. They 
show more plainly in the next section, x 550. 
Fig. 4. Next section of the definitive nucleus shown in Fig. 3. The polar 
nuclei of which it is composed are evidently not completely fused. It contains at 
least three nucleoli. The somewhat torn nucleolus to the extreme left seems to be 
a section of one of the others which has drifted there. It, however, prevents one 
from following out the vermiform generative nucleus which shows just below it. 
x 550. 
Fig. 5. Upper part of embryo-sac shown in Fig. 2 under greater magnification. 
X 550 - 
Fig. 6. Portion of embryo-sac with much coiled second male generative nucleus 
fertilizing the definitive nucleus. The latter contains only one nucleolus, but has 
an irregular outline with one sharp constriction which may mark the point of fusion 
of its polar nuclei, x 200. 
Fig. 7. Definitive group from Fig. 6, under greater magnification, x 550. 
Fig. 8. Oosphere with male generative nucleus just touching its nucleus. 
X 550 - 
Fig. 9. Definitive group from same sac as furnished Fig. 8. The second 
generative nucleus is in an advanced stage of fusion with the definitive nucleus, but 
still shows its vermiform shape very distinctly, x 550. 
