SUMMARY AND CONCLUSIONS 59 
SUMMARY AND CONCLUSIONS 
The results presented in the foregoing pages have been derived 
from a study of 23 species representing 9 genera of the Rubiaceae. 
In view of the great size and complexity of the family as at 
present understood, any conclusions based upon so small a pro- 
portion of the whole segregate may be applied with probable 
truth only to the genera represented by the species studied. 
Of the lot, the Galieae have been the most thoroughly 
- studied, and this group has been found to present a high degree 
of homogeneity, and the characters ascertained, with one exception 
to be noted below under 5 may be received as applying with only 
um differences to all the plants of Galicaz. 
. In all the plants considered, excepting in those of the genus 
a two ovules are present. Their primordia arise in the 
floor of the ovary on either side the floral axis, and develop in 
such a manner as to produce approximately anatropous ovules 
provided with a single integument and with a greatly reduced 
nucellus which is not, to be distinguished except at an early age, 
when it takes the form of a cap consisting of a single layer of cells 
crowning the archesporium. Inthe Compositae this layer forms a 
complete investment of an unicellular archesporium. It would 
appear, then, that the nucellus in these Rubiaceae is suppressed, a 
view however which is hardly in accord with the facts ; for the ap- 
parent lack of a nucellus such as we find in the Compositae, may 
be regarded as a result of the thickening of the tissue of the pri- 
mordium about the sides of the archesporium and the origin of the 
much thickened integument nearer the morphological apex of the 
primordium. According to this interpretation the nucellus و‎ 
marked by the more abundant growth of its sides and its intimate 
relation to the integument. 
This circumstance, if, as I hold, a fact, leads toa a n 
delimiting the nucellus as ordinarily defined, a difficulty however 
no greater than that encountered in defining any organ when 
. viewed in the light of modern morphological conceptions. 
2. In the Spermacoceae there is, in addition to the integument, 
a second outgrowth, derived from the funiculus and here called a 
strophiole. This structure contains the vascular supply of the 
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