ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
341 ) 
Extra-floral Nectaries.* — Herr S. Aufreclit has studied the structure 
and development of extra-floral nectaries, especially in Ricinm communis , 
Impatiens glandulifera , Viburnum Opulus , Passijlora cserulea , and Acacia 
lophantha . In Ricinus and Passijlora the secreting epiderm consists of 
two, in the other examples of only a single layer of cells. In Ricinus , 
not only the epidermal cells, bat also those of a hypodermal layer, and 
of still lower regions of the cortical tissue, take part in the formation. 
In all cases the cells contain a finely granulated, nucleated, colourless or 
pale yellow protoplasm. There is always a strongly developed vascular 
system, consisting either only of spiral or also of other kinds of vessels, 
ending immediately beneath the glandular tissue. The secretion escapes, 
in Ricinus and Passijlora , by rupture of the cuticle, in Impatiens through 
the cuticle, in Viburnum through stomates, in Acacia through slender 
pore-canals. Only in Acacia were trichomic structures observed on the 
secreting surface. In Acacia no secretion of nectar could be detected ; 
in the other instances it consists of a sugar which does not reduce copper 
oxide in the cold. No starch was observed in the nectary-tissue. Tannin 
always occurs in large quantities, usually accompanied by anthocyan ; 
also calcium oxalate in various forms. The function of this latter is to 
serve as a conveyor of the carbohydrates. The anthocyan plays the part 
of attracting noxious insects away from the flower ; while the tannin 
protects the nectaries from injury by insects, especially ants. 
Seeds of the Ampelideae.f — Prof. A. N. Berlese has studied the 
form, structure, and development of the seed in various species of 
Ampelideae belonging to the genera Vitis, Ampelopsis, Cissus, Tetrastigma , 
and others. The following are the more general results obtained. 
The ovary is bilocular, and has originally four ovules, of which 
three are usually abortive. The embryo-sac originates from the third 
cell of the axile row resulting from the development and division of the 
hypodermal mother-cell. There are two antipodals and two synergids ; 
the former have a very short existence. During the development of the 
embryo-sac two caps (calottes) are formed ; the inner one soon disappears 
entirely, while traces of the outer one remain for a considerable time 
near the micropyle. The ovule, at first orthotropous, becomes rapidly 
anatropous. It has two integuments, which persist in the ripe seed ; 
the outer one is always composed of three layers. The suspensor 
remains attached to the embryo till its maturity ; the plumule is rudi- 
mentary ; the embryo is straight ; the cotyledons are opposite and curved. 
The greater part of the endosperm remains in the mature seed ; it is 
oily, rarely farinaceous, and contains large aleurone-grains ; each 
aleurone-grain encloses a crystal of calcium oxalate isolated or enclosed 
in a globoid, and sometimes also a crystalloid. 
Embryo of Palms.J — M. H. Micheels describes the form of the 
embryo in a number of different species of palm, which is subject to 
considerable variation. The form is usually that of a cone (or some form 
derived from the cone), compressed or not, more or less rounded or 
* ‘Beitr. z. Kenntniss extrafloraler Nectarien,’ Zurich, 1891, 44 pp. See Bot. 
Centralbl., 1892, Beih., p. 441. 
f Malpighia, vi. (1893) pp. 293-324, 482-536 (9 pis.). 
X Bull. Soc. Roy. Bot. Belgique, xxxi. (1892) pp. 174-8. 
