96 SQMBIARY OF CURRENT RESEARCHES RELATING TO 



of ziuc, indicate that tlicy arc composed of slightly lignificd 

 cellulose. 



The non-calcareous cystoliths are found only in the sclerenchy- 

 matous idioblasts of the medullary parenchyma, and are not, like those 

 j)reviously described in Ficus elastica and australis, of a pathological 

 character. They occur also in similar situations in Goldfussia glomerata 

 and Buellia ocliroleuca. 



Tannin and Aleurone.* — J. Diifour finds that the cells of the 

 embryo of Borrago are filled with aleurone-grains and drops of oil, 

 and contain also a quantity of tannic acid. The size of the aleurone- 

 grains varies from 1-25 /x, the usual size being from 6-13 /jl. No 

 trace o.f crystalloids was observed. The aleurone-grains of most 

 Borragineaj are insoluble in water, but dissolve at once on addition of 

 potash-ley, with explosive phenomena. In opposition to previous 

 statements, he found tannin present in large quantities, not only in 

 the seeds of Borrago officinalis, but some also in those of the majority 

 of the plants examined ; for example, in all species of Borraginefe, and 

 in some CompositiB and CEnothereaj. In the former order Myosotis 

 contained the largest quantity. From Eanunculacete and Solanefe it 

 appeared to be entirely absent. The reagent employed in detecting 

 it was usually potassium chromate or ferric chloride, FcaClo. 



The greater number of seeds which contained tannin were without 

 endosperm ; it occurred in the embryo itself. In Mirahilis there is an 

 endosperm the cells of which contain nothing but starch, both tannin 

 and aleurone-grains being present in the embryo. The question 

 whether tannin enters into the composition of the aleurone-grains 

 when they are both present in the same cell, the author is unable at 

 present to decide. 



Phaenological Inversions.f — By this term L. Kalin understands 

 the inversion of the ordinary succession of blossoming in flowers, 

 caused by abnormal meteorological conditions. From observations 

 extending over twenty years in the botanic garden at Giessen, he 

 states that the time of the first opening of flowers depends not only on 

 the minimum daily temperature, but also on the amount of precipita- 

 tion of moisture, and lays down the following general rules : — (1) The 

 blossoming of any particular plant depends on a certain sum of tem- 

 perature, which should be reckoned in our latitudes from about the 

 1st of January ; and, secondly, on the height of the mean daily 

 minimum temperature. (2) A minimum above the mean corresponds 

 to an earlier, a minimum below the mean to a later mean blossoming. 

 (3) The influence of the daily minimum is balanced by a high daily 

 sun-maximum, by precipitation of moisture at the time of blossoming, 

 by general moisture, by a striking deficiency in the daily precipitation, 

 by general dryness, and by the action of late frosts. (4) High sun- 

 maxima may altogether counteract the retarding action of a low daily 



* Dufour, J., ' Etudes d'aiiatomic ct de physiologie vegetales.' Lausanne, 

 1882. See Bot. Centralbl., xii. (1882) p. 156. 



t Ber. Oberliess. Gesellscli. Nat. u. Heilkunde, xxi. (1882) pp. 11.3-44 (1 pi.). 

 See Naturforscher, xv. (1882) p. 401. 



