ZOOLOGY AND BOTANY, MICEOSCOPY, ETC. 103 



year ; and the same is true of all those Conifers in which the leaves 

 arc in clusters of twos or threes, but not of those in which the leaves 

 are solitary. A secondary growth appears to take jjlace in the second 

 year, which is reijeated in the third ; the increase in length being d\io 

 chiefly to a growth of the cells in the leaf-sheath. In other trees, 

 the mode of growth of the leaves is of two different kinds. Either the 

 increase in size takes place from below upwards, so that the upper- 

 most leaves are the largest, as in the lime, birch, and elm, or the size 

 of the leaves at first increases upwards, but again decreases rapidly 

 towards the apex of the branch, as in the maple and horse-chestnut. 

 In the beech both modes occur. The leaves on the main branches of 

 Pinus excelsa are larger than those on the lateral branches. 



Influence of Electricity on Growth.* — The object of Dr. Holde- 

 fleiss's researches was to determine what influence, if any, was 

 exerted on a crop of roots and potatoes by a weak galvanic current 

 passing through the soil. In the field, copper plates, 50 by 80 cm. 

 square, were sunk vertically, so that one plate covered two drills; 

 the plates were 56 m. distant, and were connected with 14 Meidinger 

 elements. In a further experiment there was a combination of zinc 

 and copper plates without a battery, placed at a distance of 33 m. 

 apart, and a third experiment was made with another arrangement 

 of pairs of plates, whereby a stronger current was produced. 



As the result, a constant current was observed, but no influence 

 appeared to be exerted on the growth of the crop as regards quality 

 or quantity, when under the influence of the first arrangement ; under 

 the second set of conditions, the crop at first was forwarded, but not 

 later on ; and an increase in yield amounting to 15-24 per cent, was 

 remarked in the third case. 



Influence of Calcium Sulphide on Barley.f — The material 

 employed by Herr J. Fittbogen to ascertain the effect of calcium 

 sulphide on the growth of barley was the ash of two sorts of brown 

 coal, containing 3 • 85 and 2 • 74 per cent, respectively of the compound. 

 A known quantity of artificially prepared sulphide was also used, 

 mixed with the usual mixture of plant-food, together with sand. In 

 the earliest stages of growth, the harmful action was perceptible, and 

 as growth proceeded the poisonous action showed itself by producing 

 white and brown markings on the leaves, which markings gradually 

 spread over the vv^hole leaf. These spots, when microscopically 

 examined, were found to indicate the cells which were emjjty and 

 destitute of chlorophyll ; moreover, the presence of calcium sulphide 

 seemed to retard growth. This action seems to be due to the forma- 

 tion of sulphuretted hydrogen, produced by the medium of water, 

 the oxygen of the soil also being removed from the service of the 

 plants. It was thought probable that the calcium hydroxide formed 

 by the decomposition of the sulphide might also prove detrimental ; 



* Journ. Chem. Soc— Abstr., xlviii. (1885) pp. 1152-3, from Bied. Centr., 

 1885, pp. 392-3. 



t Journ. Cheru. Soc. — Abstr., xlviii. (1885) p. 1154, from Bied. Centr., 1885, 

 pp. 385-92. 



