532 SUMMARY OF CURRENT RESEARCHES RELATING TO 



from which liquid water exudes. He describes the water-pores of 

 150 species, distributed through 91 genera and 36 families. He 

 appears to have exercised great care to avoid errors from the possible 

 presence of dew upon the leaves. In order to ascertain the amount of 

 water in the stems of the plants exhibiting this phenomenon, he made 

 use of double scissors, by which a piece about half an inch in 

 length could be cut out at one stroke, thus diminishing the chances of 

 affecting the relative amounts of air and water in the part at the 

 moment of separation. By the use of this simple contrivance, he has 

 shown that the amount of air and water in a vigorous plant varies 

 considerably during the day, even when the specimen is kept under 

 uniform external conditions. Most of his observations were made 

 ujiou wild plants in ojien fields. 



HypoxantMn in the Potato.* — E. Schulze finds that in the 

 precii^itate produced in the sap of the potato by phosphor-tungstic 

 acid after removal of the albuminoids, together with peptones, other 

 nitrogenous substances of the nature of xanthin are present. He 

 succeeded in obtaining a substance which gave the reactions of 

 hypoxauthin. Approximate quantitative determinations gave an 

 average percentage of 0-00355 gr. of hypoxauthin in 100 ccm. of 

 the sap. 



Function of Tannin in Metastasis. | — E. Kutscher thus sums up 

 the results of a series of observations on this subject : — 



1. Tannin may be an excretory product of metastasis, as in Ricinus, 

 Phaseolus, the roots of many Cycadese, and in the leaf-glands of Hype- 

 ricum perforatum. It is in this case not distributed through all the 

 cells of the tissue, but occurs only in special excretory cells. In 

 these it is often mixed with pigments, and disappears along with 

 them ; it appears to have no other function. It usually causes a blue 

 reaction with iron. 



2. It may be of further use in metastasis ; as in Yicia Faba, and 

 Helianthus annuus and tuherosus. It is then formed only during the 

 construction of primary tissue and on its first difi'erentiation, as in tho 

 growing point, the cambium, in young fruits, and in the foz'mation of 

 secondary roots. It is at first formed in all the cells of the tissue, 

 permeating also the cell-walls and nucleus, and then passes into 

 special tissues. A rai)id consumj)tion of tannin also takes place 

 within the bud ; this becomes afterwards slower but continuous, so 

 that at the end of the period of growth only traces of it remain. It 

 cannot, however, be stated with certainty that it serves directly as the 

 formative material for primary meristem. Its chemical properties and 

 life-history point to the conclusion that it serves as a medium for 

 respiration ; i.e. that it undergoes oxidation. 



Laws wMcli regulate the Production of Male and Female 

 Flowers. :f — Comparing male with female maple trees, T. Meehan 



* Landw. Vers.-Stat., xxviii. (1882j pp. 111-5. See Bot. Centralbl., xii. (1882) 

 p. 257. 



+ Flora, Ixvi. (1883) pp. 33-42, 49-64, 65-74 (2 pis.). 

 X Proc. Acad. Nat. Sci. Philad., 1882, pp. 89-92. 



