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1903] CURRENT LITERATURE 15f 
ASTRUC has brought toa conclusion his work on the acidity of plants. '5 
He finds that in non-succulents vegetable acids are made chiefly in the young 
parts ; that is, in the particular regions of cellular activity, of maximum tur- 
gescence, and of oxidation. These acids are neutralized or etherized little by 
‘little, as has already been shown by other observers. These facts serve to 
explain the distribution of relative acidity in plants, which gradually dimin- 
ishes as the development of the organs advances. In succulents, on the con- 
trary, the acidity depends upon slight changes in the external conditions, and 
these make comparisons sometimes difficult. Thus, the free acids in the Cras- 
sulaceae present within a single day enormous variation both in formation 
and in distribution, so that it is quite impossible to lay down any absolute rule 
for the occurrence of acids in different leaves of even the same plant. From 
a great number of experiments, however, Astruc has concluded that the for- 
mation of greater or less amounts of malic acid during the night depends on 
photosynthesis during the day, and is intimately related to respiration and to 
the greater or less value of the internal respiratory ratio during the night. 
Incidentally he notes a somewhat remarkable fact, that oxygen is not fixed by 
the cell when the protoplasm is anesthetized by ether or by chloroform. Dur- 
ing the day malic acid diminishes in amount under the influence of respira- 
tion and photosynthesis, but if the normal conditions for the plant are 
changed, that is, if there intervene external causes capable of influencing cell 
activity, these causes will also influence acidity. Thus sectioning of leaves 
or changing the constituents of the atmosphere enveloping the plant will 
induce notable changes in the processes of acid formation or destruction,— 
CR 
THE DEVELOPMENT of the sexual organs and fertilization in Picea excelsa 
are described in a recent article by sere 7° The pollen grain at the time 
of shedding, about the second week in May, contains two disorganized pro- 
thallial cells, a stalk cell, body cell, and tube cell. The tube begins to form 
a few days after pollination, and t ody cell at once passes into it and 
divides, giving rise to two male ated At this division the beginning of a 
cell plate appears at the equator of the spindle, but it soon disappears and 
no wall is formed; consequently the two male nuclei lie free in a common 
mass of cytoplasm, and there is no formation of two cells, as described by 
Strasburger, Belajeff, Dixon, and Coulter. The pollen tube does not branch, 
The development of the archegonium is very much as in Pinus. In the 
neck of the archegonium there are 4-8 cells with 2-4 cells ina row. There 
are usually four archegonia to each ovule, but the number varies from two to 
seven. During the growth of the egg no passage of nuclear material from 
*SAsTRuC, M. A., Recherches sur l’acidité végétale. Ann. Sci. Nat. Bot. VIII, 
17:109. 1903. 
6 MIYAKE, K., On the development of the sexual organs and fertilization in Picea 
excelsa. Ann. Bot. 17 : 351-372. pls. 16-77. 1903. 
