SUMMARY AND CONCLUSIONS 61 
sitic habit of growth, must now be thrown aside. This conclusion 
was suggested inferentially by Goebel* in connection with his ob- 
servation on the ovules of Crinum Asiaticum of which he remarked : 
“Sie zeichnen sich durch eine, sonst nur bei Schmarotzerpflanzen 
bekannte Eigenthümlichkeit aus, sie sind nackt, es fehlen die 
sonst in Ein- oder Zweizahl vorhandenen Integumente.” 
4. The archesporium throughout contains a number (7-15) of 
megaspore mother-cells, the largest number occurring in the spe- 
cies of the Galicae. Each megaspore—barring the arrested ones 
at the side of the archesporium—divides twice to form four mega- 
spores, which, except very infrequently, are not separated by 
walls. This condition is comparable to that described as occur- 
ring with some frequency in Zichhornia} and Avena.} All the 
megaspores are both morphologically and physiologically equiva- 
lent. It is, in consequence, impossible to pick out with the eye 
the functional megaspore, which appears usually to be the outer. 
As Koernicke § has recently emphasized, the embryo-sac cell in 
the great majority of Phanerogams is derived from the last mega- 
spore, 2 e., the one at the chalazal pole, because usually the divi- 
sions which give rise to the megaspores are such as to give the 
largest proportion of plasma to that cell, a phenomenon which he 
holds to be connected with its more favorable position with refer- 
ence to the source of nutriment. This view finds support in the 
facts here summarized in so far that the larger number of mega- 
spores and undivided megaspore mother-cells form a nutritive tis- 
sue surrounding more or less completely the embryo-sac cell 
which arises near the longitudinal axis of the mass. That the 
functional megaspore, 7. ¢., the embryo-sac cell is found near the 
middle, and not in the sides of the archesporium is due, I hold, to 
the mechanical relation between the cells brought about by the 
growth of the ovule which is such as to produce no unequal pres- 
sure on the archesporium. 
Vi e eeg Schilderungen, t1: p. 
1 Smith, W. R. A Contdibition to de Life History of the Pontederiaceae. Bot. 
Gaz. 15: m 
189 8. 
iCannon, W. A. A morphological Study of the Flower on Pes of the Wild 
Oat, Arena fatua L. Proc. Cal. Acad. Botany, III. 1: 329 
Studien an Euibeyötóck- -Matterzellen, Sitzungsber. de Néeaéchen. Gesellsch. 
Natur- und Heilkunde zu Bonn. 
