ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
405 
entirely disappeared in the ripe seed, and the cavity is surrounded 
immediately by the parenchymatous cells, thus communicating directly 
with the intercellular spaces of the parenchyme. The canal is usually 
obliterated in its lower portion. 
Crest of Seeds.* * * § — Mr. C. Robertson suggests that the purpose of the 
crest of many seeds, where it is not sufficiently large to add to their 
attractiveness to frugivorous birds or other animals, is to furnish a 
handle by which they can be carried away by ants, and their dissemina- 
tion thus secured. 
Domatia. I — Mr. A. C. Hamilton gives an account of the occurrence 
of these structures in a number of Australian and other plants. Their 
most common form is that of a tuft of hairs in the axil of a vein on the 
under surface of the leaf, with which is connected an opening through 
the epiderm. The author classifies them under 5 heads, viz. : — (1) Circular 
lenticular cavities on the under side of the leaf, each with a small open- 
ing and a thickened rim ; (2) pouches formed by a widening of the 
principal and lateral veins at the axils, the space being filled in with 
tissue so as to form a triangular pouch or pocket ; (3) depressions or 
hollows formed by a thinning of the leaf-substance at the axils ; 
(4) bunches of hairs in the axils of the principal and secondary veins ; 
(5) denser bunches of hairs at the vein-axils of hairy leaves. The author 
gives the number of species in which domatia have been observed by 
himself or others as nearly 300, about one-half of these belonging to two 
natural orders, Rubiaceae (107) and Tiliaceae (40). The domatia are 
generally, but not always, inhabited by mites ; but the author does not 
accept Lundstrom’s view that their main object is connected with com- 
mensalism. He considers it more probable that their primary function 
is concerned with the absorption of gas, vapour, or water. 
Morphology of Aquatic Plants.^ — The conclusion arrived at by 
Goebel that the narrow ligulate leaves of Sagittaria sagittsefolia are 
the results of a reversion of the mature sagittate leaves to an earlier and 
simpler type, is applied by Herr W. Wachter to other aquatic plants. 
In S. natans there are two forms of leaf ; the earlier ones are ligulate, 
and (in contrast to those of S. sagittsefolia) are persistent, the mature 
leaves having an elliptical lamina. These merely represent different 
forms of the same leaf, the difference being apparently due to conditions 
of light. The results were not so decisive with S. chinensis, Eichliornia 
azurea, or Hydrocleis nymphoides. 
A detailed description is given of the anomalous Weddellina squamu - 
losa , belonging to the Podostemaceae. 
Leaves of Aquatic Gentianace8e.§ — M. E. Perrot describes a pecu- 
liarity in the structure of the leaves of certain species of Villarsia and 
Limnanthemum, In L. nymphdeoides the under surface of the floating 
leaves exhibits a number of brown spots, formed of cells with straight 
somewhat thickened walls, containing a brown pigment of the nature of 
tannin, and numerous grains of chlorophyll. At these spots the epi- 
* Bot. Gazette, xxiii. (1897) pp. 288-9. 
t Proc. Linn. Soc. N. S. Wales, xxi. (1896) pp. 758-92 (1 pi.). Cf. this Journal, 
1888, p. 87. % Flora, lxxxiii. (1897) pp. 367-97 (21 figs.). 
§ Journ. de Bot. (Morot), xi. (1897) pp. 195-201 (4 figs.). 
