258 BOTANICAL GAZETTE [MARCH 
Comparative anatomy of stomata.—From an examination of over 30 
species of seed plants, taken from widely scattered genera, WarNCKE* finds 
upon many very divergent forms of stomata upon the different organs. So 
marked is the diversity that in some instances each organ seemed to possess 
its own particular type. On the whole, however, stomata on stems and 
petioles are much alike and are usually larger and with thicker walls than 
those of foliage leaves. The most divergent forms are those occurring upon 
rhizomes and in the epidermis of the inner side of sheaths. The very different 
external conditions will at least partially account for the greater amount of 
submergence below the level of the epidermis, for the thicker cell walls 
of the stomata of more exposed organs, and for the tendency toward loss of 
function and suppression upon the submerged and subterranean parts, but 
it is quite inadequate to explain the occurrence of two such entirely diverse 
types as those found upon the outer and inner surfaces of the sheath of Zea 
Mays. As might be expected, a close relationship is found to exist between 
the type of stomata and the general outline of the epidermal cells. 
No phylogenetic sequence is revealed in the various forms examined; 
indeed, the investigator does not believe that Porscu’s is warranted in his 
conclusions regarding the phylogenetic importance of the types of stomata, 
since he compared as homologous the stomata of various organs now found 
to differ to a marked degree upon the same individual, and even, in a few 
instances, upon different parts of the same organ.—Gro. D. FULLER. 
Embryo sac of Crassulaceae.—In 1908 WENT described the ovule and 
embryo sac of the Podostemaceae, in which he found among other peculiarities 
an empty cavity or “Pseudoembryosack” extending from the base of the 
short sac to the chalazal region. This has led Miss RoMBACH™ to investigate 
the related Crassulaceae in the hope of throwing some light upon the signifi- 
cance of this peculiarity. Eight species were examined, which showed agree- 
ment in all essential features. A subepidermal cell of the very reduced nucellus 
cuts off one parietal cell and then divides to form four megaspores, the inner- 
most of which gives rise to an embryo sac of the ordinary eight-nucleate type. 
During the early development of the endosperm and embryo the base of the 
sac with the antipodals grows downward through a central strand of loose, 
elongated cells until it reaches the chalaza. 
The author believes that here are present side by side two processes: 
- the outgrowth of the embryo sac, and cavity formation by the nucellus. In 
the Podostemaceae it is supposed that the embryo sac formerly filled all the 
4 WARNCKE, FREDERICK, Neue Beitrige zur Kenntnis der Spaltéffungen. Jahrb. 
Wiss. Bot. 50: 21-66. 1911. 
5 —. O., Der Spaltéffungsapparat im Lichte der Phylogenie. Jena. 19°5- 
%6Rompacu, Sara, Die Entwicklung der Samenknospe bei den Crassulaceen. 
Rec. Trav. ck. ‘Nécslandads 4: 182-200. figs. 10. 1911. 
