ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
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sido of the organ, or of buds or slioots on tho upper side; hypotrophy , 
when the reverse is the case ; amphitrophy , when the growth is greatest 
on the shoots and buds on the sides of the mother-shoot. This is a con- 
trivance for obtaining greater light by the leaves of very leafy trees, or 
of shrubs growing in the shade. 
Dissemination of Plants by Buffaloes.* * * § — Mr. E. L. Berthoud calls 
attention to the facility with which seeds, and even roots, of plants may 
have been carried from one part of North America to another in the 
hairy “ pads ” on the front of the buffalo during its annual migrations. 
He attributes to this, and not to the survival of an Arctic flora, the 
occurrence of many plants, such as species of Cactus , in the vicinity of 
Lake Winnipeg. 
Dissemination of the Seeds of Oxalis stricta.|— - Mr. E. Walker 
describes the mechanism by which the seeds of this plant are violently 
thrown out of the capsule when ripe, frequently to a distance of three 
feet. The erect capsule becomes flaccid on maturity, and the active 
agent in the propulsion is the outer coat of the seed itself, which consists 
of a translucent, shining, membranous envelope stretched tightly over 
the seed. When it bursts, it suddenly and elastically turns inside out, 
and projects the seed by doubling back against the axis of the capsule. 
Physiology and Biology of Seeds.J — According to Prof. A. Tschircli, 
the main purpose of the hard sclereid-layer of the testa of seeds is a 
protective one, while that of the mucilaginous epiderm of certain seeds 
is to fix them in the soil while germinating. The testa of all seeds has, 
in addition, in the young state, a layer of parenchymatous cells, which, 
in almost all cases, disappears on maturity. This layer is a transitory 
receptacle for food-materials. Cell-nuclei are present in all such recep- 
tacles, whether in the endosperm or the perisperm. There is always a 
means of conduction of the reserve-materials from the endosperm or 
perisperm to the embryo, varying according to the structure of the seed. 
When seeds of Dicotyledons germinate on the surface of the soil, the 
aleurone is dissolved, and its place is taken by chromatophores, which 
divide actively. In Lupinus chlorophyll is stored up in large quantities 
in the cotyledons even of unripe seeds ; this disappears almost entirely 
when the seed is ripe, and is again formed during germination. 
Parasitism of Cynomorium.§ — Prof. G. Arcangeli has carried on a 
further series of experiments with regard to the parasitism of Cyno- 
morium coccineum , especially on Atriplex nummularia. He failed to find 
any true intramatrical thallus corresponding to that of the Rafflesiacese 
and Balanophoraceae. A good development of the Cynomorium was also 
obtained on a number of other plants belonging to a variety of natural 
orders. 
Growth in Thickness of Trees. |j — In reply to Prof. R. Hartig, 
Herr L. Jost adduces further arguments in favour of his view as to the 
* Bot. Gazette, xvii. (1892) pp. 321-6. 
f Proc. Acad. Nat. Sci. Philadelphia, 1892, p. 288. 
% Verhaudl. Schweiz. Naturf. Gesell. Davos, Ixxiii. (1892) pp. 260-6. Cf. this 
Journal, 1892, p. 233. 
§ Bull. Soc. Bot. Itah, i. (1892) pp. 345-7. Cf. this Journal, 1892, p. 391. 
II Bot. Ztg, 1. (1892) pp. 489-95, 505-10. Cf. this Journal, 1892, p. 499. 
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