7361 SUMMARY OF CURRENT RESEARCHES. 



odour is easily perceived and distinguished from somewhat similar 

 smells. For detecting the presence of arsenic in urine, the residue, 

 after treatment with nitric-sulphuric acid, should be saturated with 

 ammonia, and then a few cubic centimetres of magnesia mixture added. 

 After standing for 24 hours the sediment is washed into the culture 

 flask. 



Besides species of Penicillium and Aspergillus, the Mucorinse also 

 give the reaction. The author mentions that P. hrevicaule exhibits 

 macroscopic differences on different media such as apple, pear, potato, 

 bread. 



Distribution of Alkali in Vegetable Tissue.* — Herr A. C. Hof 

 demonstrates the presence and location of alkali in vegetable tissue by 

 the method adopted by Prof. Ehrlich in animal histology. The reaction 

 is applicable only to dry tissues, and is monochromatic. The pigment 

 used is iodine-eosin which forms a deep red aqueous solution, but is not 

 soluble in ether, chloroform, or toluol. On the other hand, when acid is 

 added, the precipitate is but slightly soluble in water, though easily in 

 organic solvents. When a dry tissue is treated with the acid ethereal 

 solution, the parts containing alkali are stained deep red owing to 

 chemical union of the free pigment acid and the tissue alkali. The 

 solution is made by adding to the alkaline solution of iodine-eosin u 

 corresponding quantity of acid and shaking the precipitate up with 

 ether. The supernatant ethereal solution of iodine-eosin-acid is then 

 ready for use. After ascertaining that the glass vessels, &c. are free 

 from alkali, the sections are immersed in the staining fluid. Those 

 parts where alkali is present are at once stained. They are then trans- 

 ferred to pure ether, which is renewed until the ether remains quite 

 clear. The still wet specimen is then at once mounted in neutral balsam, 

 the ordinary balsam being quite useless for the purpose. The morphotic 

 elements of preparations treated in the foregoing manner retain their 

 shape perfectly, and show in those places where alkali is present a deep 

 red staining, the non-alkaline parts remaining uncoloured. 



Labelling Blocks and Slides.t — Mr. C. M. Thurston labels celloidin 

 and paraffin blocks in the following way. The number or name is written 

 on one end of an oblong piece of filter-paper ; on the other end is placed 

 a drop of egg-albumen, and this end is pressed on the surface of the block 

 opposite that to be sectioned. The albumen is coagulated sufficiently 

 well to fix the label firmly enough for ordinary purposes. 



The author % labels slides and cover-glasses by writing on them with 

 a fluid composed of equal parts of egg-albumen and glycerin to which 

 enough lampblack has been added to pigment it sufficiently. The 

 solution flows readily from a steel pen. The writing is then fixed in 

 the flame. . 



Bbhrens, H. — Mikrochemische Technik. 2nd edition, Hamburg, 1900, Svo. 68 pp. 

 Hanausek, T. F. — Lekrbuch der Mikroskopischen Technik. 



Stuttgart. 1900, part i. Svo, 160 pp. and 105 figs. 



* Bot. Centralbl., lxxxiii. (1900) pp. 273-80 (1 pi.). 



t Journ. Applied Microscopy, iii. (1900) p. 894. % Tom. cit., p. 900. 



