ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
211 
As respects tlie group of perigynous Dialypetalae, M. Chatin finds, at 
all events in the two largest orders, the Leguminosae and the Rosacese, 
a very general difference between the woody and the herbaceous species ; 
the former having, as a rule, only one, while the latter have several 
vascular bundles in the petiole. 
The hypogynous Dialypetalae are divided into 6 classes, according to 
the number of vascular bundles in the petiole, whether 1, 3, 5, 7, 9-11, 
or a larger number, some natural orders having representatives in nearly 
all the classes; hut the complete union of the vascular bundles into one, 
a sign of the highest development, is much less common than in the 
Corolliflorae or the perigynous Dialypetalae Climbing plants, as a rule, 
have a large number of vascular bundles in the petiole. 
Peltate Leaves.* * * § — M. C. de Candolle distinguishes two kinds of 
peltate leaves, “ epipeltate ” and “ hypopeltate.” In the former the 
lamina is, in the growing state, intercalated between the petiole and 
the upper region of the stem ; while in the latter it is the outer or lower 
face of the growing point of the future leaf which produces the base of 
the lamina, and the petiole is thus intercalated between the lamina and 
the upper region of the stem. M. de Candolle believes that the forma- 
tion of the hypopeltate leaves can always be traced to a law of compen- 
sation, in virtue of which a great development of the upper portion of 
the growing point excludes the possibility of a secondary increase at the 
base of the lamina. 
Leaves of Ficus.j — Prof. M. Moebius describes the structure of the 
leaves of various species of Ficus , especially in relation to the thickness 
of the epiderm, the cystoliths, and the pits ; each species has a charac- 
teristic structure on these points. The epiderm of the upper is always 
thicker than that of the under surface, either from the cells being larger, 
or from their being arranged in a larger number of rows. The cysto- 
lith- cells are modified trichomes. They are of two kinds : either 
modified specially enlarged or ordinary epidermal cells. The presence 
of pits is not connected with the external nature of the leaf ; they are 
derived from triclioniic structures. Ficus australis has mucilage-cells, 
but the nature of the cell-contents has not been accurately ascertained. 
Defences of Plants.:]: — M. A. Gilkinet gives a succinct account of 
the various modes of defence exercised by plants against herbivorous 
and ’other enemies : — The production of spines, especially on young 
plants and young organs ; the formation of alkaloids, glucosides, oxalic 
acid, essences, and other poisonous or unpalatable substances ; the exu- 
dation of viscid secretions ; myrmecophily, &e. 
Bulb of Erythronium.§ — Dr. A. P. Winter describes the structure 
and biology of the bulb of the dog’s-tooth violet, Frytlironium dens-canis. 
The flower-stalk obtains its nourishment from a fleshy “ nutrient leaf” by 
which it is surrounded ; the lower part of the flower-stalk swells up into 
the rudiment of next year’s bulb. The plants are of two kinds ; — annual, 
* Bull. Trav. Soc. Bot. Geneve, 1897. See Bull. Soc. Bot. France, xliv. (1897) 
Kev. Bibl., p. 378. 
t Ber. Senckenberg. Naturf. Gesell., 1897, pp. 117-38 (2 pis.). 
t Bull. Acad. R. Sci. Belgique, 1897, pp. 1120-38. 
§ Oesterr. Bot. Zeitschr., xlvii. (1897) pp. 331-5. 
