107 
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pollen is scraped out of the anthers by the hairy style and brushed off 
before the stigmas open, thus securing cross-fertilization. The 
development of the pollen is normal. The stigmas are held together 
till mature by interlocking papilla. The hairs on the style become 
partially mtroverted, thus freeing the pollen. 
The pollen-spore contains two nuclei, the larger of which, the 
vegetative, becomes disorganized shortly after entering the pollen- 
tube, while the smaller spindle-shaped generative nucleus persists. 
The embryo-sac is cylindrical, with a gradual enlargement near 
the micropylar end, where is located the egg-apparatus, and an abrupt 
enlargment at the chalazal end, in which lie the antipodal cells. 
There are usually two sac-nuclei. 
The pollen-tubes enter the style between the bases of the papilla 
of the stigma, pass down in the strands of conducting tissue, and not 
through the central canal, around which this tissue is arranged. The 
paper was followed by an account of the methods used, and illustrated 
by figures drawn upon a large chart. 
'' Proof that Bacteria are the direct Cause of the Disease in Trees 
known as Pear-blight," by J. C Arthur, Cultures of the bacterium 
taken from blighted twigs were made in sterilized corn-meal juice. 
After a few days some of the bacteria, which had increased rapidly 
in this medium, were transferred (a drop only) to another sterilized 
preparation of corn-meal juice. After a few days another transfer 
was made, and this was continued until the sixth culture had been 
reached, when there was presumably but an infinitesimal amount of 
the original diseased juice present. Inoculations made with the bac- 
teria of the last culture resulted in producing the blight as certainly 
and rapidly as in the first case. 
The crucial experiment was made by filtering a watery solution 
containing the bacteria, and then inoculating with the bacteria on the 
one hand and the filtration on the other, resulting in blight in the 
former and none at all in the latter case. 
u 
The Mechanical Injury to Trees by Cold," by T. J 
There are two kinds of mechanical injury due to a low temperature, 
viz.: (i) The cracking and splitting of the bark and wood in a longi- 
tudinal-radial direction; and (2) the separation of the concentric 
layers of wood and bark, and especially the rupture of the cambium, 
thus destroying the bark and perhaps also killing the tree. 
The first injury is due to the shrinking of the tissues by cold. 
The second is due to the growth of ice-crystals in the annual rings 
on the surface of the wood. 
'* Further Observations on the Adventitious Inflorescence of Cus- 
cuta glomeraia^'' by Charles E. Bessey. A further examination shows 
that it is the universal rule of this species for the infloresence to de- 
velop from lateral adventitious buds, and that no normal inflorescence 
is developed. The adventitious infloresence always bears a definite 
relation to the parasitic roots; that portion of the stem which bears 
roots produces adventitious inflorescence, and the greater the number 
of roots the greater the mass of infloresence. No adventitious inflor- 
bear roots. 
ck)e 
