ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
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monoecious plants in the following species : — Ecbalium elaterium, Bryonia 
alba , Quercus ilicifolia, Sagittaria sagittsefolia ; also of the occurrence of 
both male and female flowers in Urtica dioica , and in Juniperus , which 
are normally dioecious. From these abnormal instances he seeks to 
establish the following laws : — That the sex is determined before impreg- 
nation ; that external conditions at the time of impregnation have a 
powerful influence on the sex of the offspring ; that up to a certain 
period the descendants may be influenced by external conditions as to 
the sex of the flowers which they will produce ; and that these influences 
may be brought to bear on every single flower on the plant. 
M. L. Trabut * * * § gives an instance of a male date-palm producing a 
large number of dates which reached an advanced stage of maturity, but 
were entirely destitute of ovules. 
Fertilization of the Date-palm.f — M. C. Naudin calls attention to 
the fact that the female date-trees grown in Provence until recently 
produced, in warm summers, half-ripe fruits which contained no seed 
and which had not been impregnated ; while during the last few years 
dates have been produced obviously containing an impregnated ovule. 
This he believes to be due to intercrossing by the pollen, carried by bees 
and other insects, of a different species, Phoenix canariensis, which has 
been recently introduced into the district. 
Sexuality of Ceratonia Siliqua.J — According to M. E. Heckel the 
usual statement that the carob is polygamous-dioecious (i. e. has on one 
plant hermaphrodite, on another male and female flowers) is inaccurate. 
On a large number of specimens examined he was unable to find any 
true female flowers, those which have this appearance being really 
hermaphrodite and brachystemonous, i.e. they have sessile anthers 
concealed at the base of the calyx, and like it, of a dark red colour. 
The pollen-grains of these stamens are slightly smaller, but otherwise 
neither the anther nor the pollen-grains differ in structure from those 
of the male or of the dolichostemonous hermaphrodite flowers. These 
brachystemonous flowers are frequently abundantly fertile. They 
appear to be on the road to become female, but have not yet reached 
that stage, The author states that the apparent parthenogenesis of 
Coelebogyne paradoxa is explicable in the same way. 
Hermaphrodite Flowers in the Larch.§ — Dr. F. Noll describes 
hermaphrodite flowers found on Larix europsea. At the base of the 
female inflorescence the tuft of leaves was completely transformed into 
normal stamens containing pollen. 
Pollination by Insects. || — From observations, made on flowering 
plants in the Netherlands, Herr H. W. Heinsius comes to the following 
general conclusions with regard to the part played by different classes 
of insects in their pollination. Allotropous diptera have a strong 
preference for flowers with exposed or half-concealed honey ; hemi- 
* Bull. Soc. Bot. France, xxxix. (1892) Sess. Extraord., p. xxxviii. (1 pi.). 
f Rev. Gen. de Bot. (Bonnier), v. (1893) pp. 97-9. 
X Bull. Soc. Bot. France, xxxix. (1893) pp. 354-9 (4 figs.). 
§ Yerhandl. Naturh. Ver. Preuss. Rheinlande, xlix. (1892) p. 57. 
|| Bot. Jaarb. (Gent), iv. (1892) pp. 54-144 (11 pis.). See Bot. Centralbl., 1893, 
Beih. p. 203. 
