220 
The investigations concerning the ovule started from 
the conditions of the Angiosperms and in order to state 
the nature of nucellus and integuments, five different 
methods were used, viz. the ontogeny, the anatomy, 
the topographical-morphology, the phylogeny and the 
teratology. 
As to the ontogeny, this is often of very little impor- 
tance for plants in general, as the organs after passing 
through a long phylogenetical development unfold imme- 
diately or grow into the now existing form, without 
repeating more or less their phylogeny, as is often the 
case in the animal kingdom. In most cases we see the 
origin of the ovule as a small papillate protrusion, around 
which both integuments originate and develop as annular 
walls in basipetal succession. 
Though the ontogeny itself gives little occasion of 
research, so much the more several botanists made use 
of teratologicals. There is much difference of opinion 
about the value we may attach to such deviations and it 
occurs rather often that investigators are willing to take 
teratologicals into consideration, when they are useful in 
the authors argumentation, whereas they are rejected, 
when in contradiction to their statement. Therefore it is 
necessary to make a very cautious use of them, and we 
may only speak with certainty of retrogressive metamor- 
phoses when deviations are found, clearly indicating a 
lower state of development as is already known in related 
plants, less far advanced in evolution. In this case they 
are of great importance and we owe many links of relation 
and origin to the observation of these teratologicals. 
À great value was always attached to what we may 
call the topographical morphology, according to which an 
organ can be determined by the place where it occurs 
on the plant. To give an example, the ovules of the 
Primulaceae, which are borne on an axial placenta, are 
