1898] THE LIFE HISTORY OF EUPHORBIA COROLLATA 423 
SUMMARY. 
The “flower” of Exphorbia corollata is an inflorescence of 
the same type as the general inflorescence or cluster of which it 
- isaunit. This is shown not only by the rudimentary develop- 
ment of perianths about the “pistil” and “ stamens,’ but more 
emphatically by the fact that the order in which the organs 
develop is not that of a flower, but of an inflorescence. 
2. This inflorescence, or cyathium, shows a marked tendency 
_ to become reduced still further by the disappearance of its car- 
. : pellate flower in the approximate ratio of one to ten. 
| ; _ 3. The development of the ovule is marked by an elaborate 
outgrowth of the nucellus into a long neck whose direction of 
| " $towth is guided by placental hairs which exert an attractive 
_ influence, causing it to bend toward them and in this way 
| Making a complete connection between the stigmatic cells and 
4 
; 
the embryo sac for the passage of the pollen tube. e 
_ 4. Ovules appear before there is any trace of carpel, being 
| Clearly of cauline origin. 
_ 5. The synergids are remarkably long, and the antipodals so 
| hemeral that only once were they discovered in several hundred 
_ Pfeparations. This suggests the possibility of their having been 
®erlooked in certain instances where they have been reported 
absent, 
6. Asarule but a single cell becomes the ancestor of all _ 
the spore mother cells in a single pollen sac. 
7. The tapetum may be clearly differentiated, at least one 
2 . preceding the pollen mother cells. It is developed from 
€ wall, 
_ 8. Abnormal cases of five and six spores instead of tetrads 
Were observed. 
_ 9 The sy napsis stage was found with perfect regularity. | 
_ 10. Evidence was obtained suggesting that the generative 
“ll may not divide. 
‘Tre UNIVERSITY oF CHICAGO. 
