Contribution to the knowledge of the 
morphological value and the 
phylogeny of the ovule and its integuments 
by 
H. R. M. DE HAAN. 
CHAPTERCT EN 
Introduction. 
The question about the morphological value of the 
ovule, has long been the subject of investigation and 
discussion, but a decisive answer is stil waited for. The 
first step to be done in order to throw light on this 
problem, is to determine to which category of organs, 
shoot, root or leaf, it can be classified as a whole. 
Especially during the nineteenth century there has been 
a good deal of disputing about this subject and nearly 
all morphologists have occupied themselves more or less 
with this question. : 
Finely their conceptions and opinions settled on three 
theories, which are to be mentioned later on, but nobody 
could give such convincing arguments, that one theory 
was accepted every where. 
Gradually, however, the botanists have adopted the 
principal idea of one of those theories, and now-a-days 
it is generally granted, that the ovule is borne by a leaf, 
at least belongs to it, but a correct interpretation of the 
nature and the origin of both integuments and the nucellus 
is very little certain. 
Recueil des trav. bot. néerl. Vol. XVII. 1920. 15 
