ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
59 
minutes to the vapour of osmic acid, and then immerses them for 
12 hours in the cliromo-formo-osmic fluid similar to Flemming’s. They 
are then washed several times, and preserved in a dilute solution of 
glycerin in water which is allowed to evaporate slowly. The staining 
reagents used are a similar solution of glycerin tinted by acetified 
methyl-green and by fuchsin. Immediately after the separation into 
two portions of the chromatic substances which form the nuclear 
plate, the granulations stained red, previously disseminated through 
the protoplasmic masses, accumulated at the poles, concentrating them- 
selves in proportion as the two halves of the nuclear plate approach 
one another. They unite so as to form a more or less complete disc, 
near which each half of a nucleole places itself. At this moment the 
nuclear membrane, stained a pale red, commences to reappear opposite 
the disc, each half of a nucleole being surrounded on the outer side by 
the disc of granulations, and on the inner side by the nuclear membrane in 
the nascent condition. The complete re-formation of the nucleus follows 
immediately. 
Growth of the Cell-wall.* * * § — From observation of a peculiar mode of 
growth which occurs in the development of the wings on the stem in 
species of Euonymus, Miss Emily L. Gregory has arrived at a conclusion 
in harmony with Strasburger’s hypothesis that growth in surface is 
effected by stretching, rather than with Krabbe’s theory j that such 
growths take place partly by intussusception. 
C2) Other Cell-contents ('including- Secretions). 
Calcium and Magnesium Oxalate in Plants.:}: — M. N. A. Monteverde 
finds that calcium oxalate is much more widely distributed in grasses than 
has been generally supposed, and its presence or absence is characteristic 
not only of the species, but also of the genus, and largely of the tribe. 
In 162 out of 550 species, and in 29 out of 94 genera examined, he 
found crystals present. Magnesium oxalate occurs in the form of 
strongly refractive spherocrystals with radial striation, or of irregular 
aggregations in the epiderm. When crystals are not present in grasses, 
all the green cells always contain drops of oil, which shows the reactions 
of a fatty oil. 
In etiolated leaves of grasses much smaller quantities of crystals of 
calcium oxalate are found than in green leaves ; their formation appears 
to be dependent directly on the light. The author believes that the 
primary calcium oxalate arises as a secondary product in various 
chemical changes of the proteids ; and that the secondary calcium 
oxalate, the formation of which goes on pari passu with the disappear- 
ance of the nitrates in the leaves, must be regarded as a secondary 
product in the new formation of the proteids. 
Yellow and Red Colouring Matters of Leaves.§ — According to 
Sig. L. Macchiati, the red pigment in the leaves of plants isolated by 
* Bull. Torrey Bot. Club, xvii. (1890) pp. 247-55 (1 pi.). 
f Cf. this Journal, 1888, p. 441. 
X ‘Ueb. d. Ablagerung v. Calcium- u. Magnesium-Oxalat in d. Pflanze’ (Russian), 
St. Petersburg, 1889, 81 pp. and 1 pi. See Bot. Centralbl., xliii. (1890) p. 327. 
§ Atti Soc. Nat. Modena. See Morot’s Journ. de Bot., iv. (1890), Rev. Bibl., 
p. xlv. Cf. this Journal, 1889, p. 240. 
