ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
503 
Dr. E. Cobelli * records his observations on the following flowers : — 
Melandrium rubrum, Philadelphus coronarius , Pulmonaria officinalis , and 
Primula officinalis, in all of which he finds arrangements for cross- 
pollination, and gives a list of the visiting insects observed. 
In the last instalment of his paper on Flowers and Insects, Mr. C. 
Eobertson j describes the structure of the flower and the mode of 
pollination, with the insect visitors, in a number of American plants, 
mostly belonging to the Orchideae, In all belonging to this order there 
appear to be adaptations for entomophily. 
Pollination of Naias and Ceratophyllum.J — M. E. Eoze has investi- 
gated the mode of pollination in Naias major and Ceratophyllum demersum, 
in both of which the whole plant, including the male and female flowers, 
is completely submerged. 
It is doubtful whether Naias major is monoecious or dioecious. The 
female flowers present a similar structure to those of Zannichellia 
j pains tr is. The ovary is surmounted by a very short style ending in 
three sepaloid expansions, which are not true stigmas. They form a 
kind of funnel into which the pollen-grains fall, and thus reach the 
stylar canal. 
In Ceratophyllum demersum the male flowers are seated on the same 
branch as the female flower, but below it. The ovary is surmounted 
by a long style entirely destitute of any stigmatic apex. In the upper 
part of the style is a canal, which appears to serve as a receiving organ 
for the pollen-grains, when they put out their pollen-tubes to reach the 
ovary. When the anthers are ripe they become detached from their 
filaments, and, buoyed up by the air-vessels which they contain, rise to 
the surface of the water, where they burst. At the same time the 
branches rise to near tjie surface, and bring the pistils into such a 
position, that the anthers floating on the surface can drop their pollen 
into the terminal canals of the styles. Fertilization, however, appears 
to take place but rarely. 
Secondary Effects of Pollination.§ — Mr. W. M. Munson gives a list 
of a number of plants in which the pollen appears to exercise an 
immediate influence on the mother-plant, and of others in which it does 
not. With several species of gourd and with Solanum Melongena seedless 
fruits were obtained when the access of pollen was prevented. The 
quantity of pollen has often a distinct effect on the form and size of the 
fruits, a large quantity promoting the full and symmetrical development 
of the fruit. 
Gynodicecism in the Iabiat3e.|| — Mr. J. C. Willis finds that, in the 
hermaphrodite plants of Origanum vulgare, there are frequently flowers 
in which one or more of the stamens are abortive ; and in the female 
plants there are occasionally flowers with one or more perfect stamens. 
Similar variations occur in the hermaphrodite flowers of other Labiatse. 
The author regards proterandry as the usual cause of gynodioecism. 
* Nuov. Giorn. Bot. Ital., xxv. (1893) pp. 5-15. 
t Bot. Gazette, xviii. (1893) pp. 47-53. Cf. this Journal, 1892, p. 820. 
X Bull. Soc. Bot. France, xxxix. (1893) pp. 361-4. 
§ Ann. Rep. Maine State Coll., 1892, pt. 2, pp. 29-58 (1 pi.). See Bot. Centralbl., 
liv. (1893) p. 165. 
11 Proc. Cambridge Phil. Soc., vii. (1892) pp. 349-52; viii. (1893) pp. 17-20. 
