1 82 SIGNIFICANCE OF MALFORMATIONS IN ORGANOGRAPHY 



abnormal development of the ovules, and quite a number of different 

 malformations of the ovule are known. The normal ovule consists, as 

 is well known, of a central body of tissue, the nucellus, which contains 

 the most important part of the ovule, namely, the embryo-sac, and is 

 invested by one or two envelopes, the integuments ; and then there is 

 the stalk or funiculus by means of which the ovule is attached to the 

 placenta. The most important question which has to be answered is 

 how do these several parts behave when phyllody takes place ? In every 

 case the phyllody is accompanied by an arrest of the nucellus, that is to 

 say, of that part which is characteristic of the ovule, and which enables 

 us to distinguish it from any other body of similar configuration ; on 

 the other hand the integuments, and often also the funiculus, experience 

 a vegetative increase and structures like leaflets may proceed from them. 



It is now to be noted that the ovules may be subjected to phyllody 

 at different stages of their development, and consequently different degrees 

 of phyllody are found. In Fig. 107, 1, an ovule is represented which 



FIG. 107. Phyllody of the ovule. 1-3 Hesperis matronalis. i. With two integuments ; Ji inner, Je outer, 

 2. Diagrammatic longitudinal section of a similar stage ; Nu nucellus. 3. Phyllody of the ovule has set in before 

 the laying down of the outer integument ; Nu arrested nucellus, y 1 "' ovular-leaflet.' 4. Alliaria officinalis. Outer and 

 inner integuments present ; G ' funicular lamina.' 1-3 After Celakowsky. 4. After Velenowsky. 



has already laid down both its integuments ; the inner one (Ji) investing 

 the nucellus is only slightly changed, and is seated upon an evident stalk 

 springing from the outer integument which has a scaphoid form as it 

 appears in diagrammatic longitudinal section (Fig. 107, 2\ and shows a 

 more marked phyllody. The phyllody has here seized upon the outer 

 integument because, as happens in by far the larger number of cases, it 

 is laid down later than the inner one, and the displacement of the nucellus 

 with its investing inner integument to the side so that it appears to 

 arise from the surface of the open outer integument, whilst it is really 

 a terminal structure, is not surprising in view of the fact that a similar 

 displacement is frequently seen in normal ovules when the integument is 

 excessively developed and occupies the apex of the ovule. In Fig. 107, 3, 

 the ovule has become a leaflet which bears the nucellus upon one 

 surface. In this case the outer integument was evidently not laid down 

 at the time when the phyllody began, the inner one was perhaps only 

 just indicated. The funiculus has likewise taken on a leaf-like form, and 



