ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 359 



phenomena observable when a very thin section of the seed-albumen 

 of Phytelephas macrocarpa is viewed by polarized light with a red 

 selenite plate. 



Extremely striking results are also given by spectrally-analysed 

 polarized light. With a transverse section of Finns sylvestris, the 

 singly refracted cambium-wall in the parts of the section lying 

 above the dark Miiller's band appears most distinctly as a dark 

 streak between the primary walls, which are of a brilliant green, 

 whilst the other parts show the cambium-wall as a coloured streak 

 between the strongly darkened, almost black, primary walls. A 

 longitudinal section through the seed-albumen, examined in a like 

 manner, gives similar striking results, which the author describes 

 and which he considers to prove his theory yet more conclusively. 



Direct Observation of the Movement of Water in Plants.* — 

 G. Capus has used the following contrivance for this piu?pose in the 

 case of plants with hollow stems, or filled only with a very delicate 

 pith, such as the dahlia, artichoke, and a species of Begonia. A 

 tangential cut is made on one side of the stem, reaching to the 

 cambium ; at a spot exactly opposite a small piece of the woody 

 cylinder is cut out, and the pith carefully removed up to the spiral 

 vessels. In this way, through a Microscope placed horizontally, a 

 sufficiently clear view can be obtained of the vessels and of the air- 

 bubbles contained in them. It may thus be seen that in cloudy 

 weather, or whenever the sun is not shining directly on the plant, 

 the vessels are injected with water ; while in direct sunshine numerous 

 air-bubbles make their appearance which gradually become larger. 



Microchemical Detection of Nitrates and Nitrites in Plants.f 

 This is possible by the reagent suggested by Wagner, viz. dipheny- 

 lamin. Molisch uses a one pro mille solution in pure sulphuric 

 acid, applying this to dry sections. If either of the salts above 

 named is present, a deep blue coloration appears, which soon changes 

 to brownish yellow. Brucin in about the same strength is nearly 

 as sensitive a test, producing a transient red or reddish-yellow colour. 

 Molisch employs this method also for approximate determination of 

 the amounts of the salts present, and finds that the percentage 

 decreases from below upward in the plant. 



New Method for the Transfer of Sterilized Broths, and the 

 Determination of the number of Living Germs in Water. J — A 

 new method has been proposed by Dr. H. Fol for preparing, steri- 

 lizing, and using nutritive fluids for the cultivation of bacteria, in water 

 and air analyses. The following is a brief abstract of the method 

 adopted. The original is accompanied by figures of the apparatus, 

 and others have been supplied in a private note. 



Originally engaged with Professor Dunant in the examination of 

 the potable waters supplied, or that might be supplied to Geneva, 

 Dr. Fol was led to adopt a plan which he considered preferable to 



* Comptes Eendus, xcviii. (1884) p. 1087. 



t Ber. Deutsch. Bot. GeseU., i. (1883) pp. 150-5. 



t Arch. Sci. Phys. et Nat., xi. (1884) pp. 557-74 (1 pi.). 



