616 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
ture insufficient to induce the commencement of germination, vacuoles 
again form in aleurone-grains. 
Chlorophyll.* — From a spectroscopic examination of the chlorophyll 
of Spirogyra , Ulva latissima , and several Ferns and Flowering Plants, 
Mr. G. Mann has come to the following conclusions : — Chloroplasts con- 
sist of a green protoplasmic ground-substance, which is rendered spongy 
by the presence of an oily material secreted by the ground-substance, 
and enclosed in a clear protoplasmic envelope. The oily material in 
Spirogyra is partly given off directly into the surrounding protoplasm, 
partly consumed by the ground-substance. Chlorophyll does not consist 
of a mixture of a yellow and a blue colouring matter, but is a green 
substance, which readily decomposes into a yellow and a blue substance. 
The first absorption-band of Kraus really consists of two bands. The 
fourth band of Kraus is probably a decomposition-product. Measure- 
ments are given of the position of the six bands in the various examples 
examined, the following being the variations: — Band 1 = A 686 *69- 
661*5; Band 2 = A 656*86-640*93; these two constitute together 
Kraus’s Band I ; Band 3 (Kraus’s Band II), centre at A 616*6 ; Band 4 
(Kraus’s Band III) centre at A 578 ; Band 5 (Kraus’s Band Y) = A 514 * 9- 
460*9 ; Band 6 (Kraus’s Band YI) = A 452-440*75. 
Sulphur in Plants.f — MM. Berthelot and G. Andre have inves- 
tigated the quantities of sulphur present — whether as sulphates, organic 
sulphur, or volatile sulphur — in the seed and in the plant during ger- 
mination, flowering, and fructification, in Sinapis alba , Camelina sativa , 
Allium cepa , Lupinus albus, TJrtica dioica , Tropseolum majus , and Arena 
sativa. They find the total quantity of sulphur to increase continually from 
germination to flowering, but the relative quantity to decrease. The 
organic sulphur reaches a maximum when the plant is in flower. They 
believe that the sulphur is not absorbed from the soil entirely in the 
form of sulphates. 
Calcium oxalate in the Bark of Trees4 — Herr G. Kraus finds that a 
large quantity of calcium oxalate is stored up in the bast-layer of the 
bark of many trees and shrubs, where it plays the part of a reserve food- 
material, i. e. it is, to a large extent, as much as 50 per cent., taken up 
again on the revival of the activity of growth in the spring. Calcium 
oxalate is soluble in many of the organic acids that occur in the tissues 
of plants. 
Crypto-crystalline Calcium oxalate.§ — Prof. G. Arcangeli has 
observed that the deposit of calcium oxalate in the cells of a large 
number of plants has the form of a crystalline powder. In the Cinchoneae 
and Solaneae these crystals have a diameter of no more than 1-3 /x ; they 
belong without doubt to the tetrahedral system. 
* Trans, and Proc. Bot. Soc. Edinb., xviii. (1889-90) pp. 394-420 (2 pis.). 
t Comptes Rendus, cxii. (1891) pp. 122-5. 
t ‘Ueb. d. Kalkoxalate d. Baumrinden,’ Halle, 1891. See Biol. Centralbl., xi. 
(1891) p. 282. 
