160 BOTANICAL GAZETTE [SEPTEMBER 
groups of angiosperms, their mutual relationship, also, will be 
indicated. 
The most important suggestions as to relationship which 
have thus far presented themselves in embryology (ontogeny) 
. may be summarized as follows: 
1. All angiosperms are essentially alike. 
2. The two sub-classes (monocotyledons and dicotyledons) 
appear to be modifications of a common type which diverged 
from one another at an early period. 
3. There is no indication that either sub-class was derived 
from the other. 
4. There are some structural indications that the monocoty 
ledons must rank lower than the dicotyledons. 
5. The vegetative rank of most dicotyledons is so nearly the 
same as to have left no vestiges on the young plant, which is 
itself vegetative. 
6. The groups into which dicotyledons and monocotyledons 
are divided are ‘‘flower-subdivisions” of a greatly multiplied, 
rather common vegetative structure; therefore, we may not 
expect to find upon the embryo or immature plant any vestigial 
record of their origin. 
7. There are some minor structural modifications, as of leaf- 
shapes, serration, lobing, etc., which appear to have arisen late 
in the history of the species, and therefore serve as indices of 
specific and sometimes generic relationship. 
GENERAL RESULTS FROM MORPHOLOGY. 
Modern morphology concerns itself so largely with the com- 
parative development as well as the comparative anatomy of 
organs as to make it impossible to draw a sharp line between it 
and ontogeny. It is by studying the development of organs in 
the immature plant, from the smallest rudiments to their full 
growth, that we have been able to make out their homologies. 
Morphology must include all of embryology and all of ontogeny- 
It is needless here to take up in detail the morphology . 
the cells and tissues of angiosperms. It is enough to remark in 
