ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 551 



Improved Method of Iodine Staining.* — F. Tobler finds that by 

 the use of lactic acid better results arc obtained with histological botanical 

 preparations stained with iodine. The original method had certain draw- 

 backs, such as the rapidity with which preparations deteriorated, and the 

 tendency of the iodine to crystallize irregularly. The application of lactic 

 acid solutions obviates these troubles to a large extent. Iodine is only 

 slightly soluble in lactic acid. If this latter reagent be allowed to diffuse 

 in from the edge of a coverslip, displacing alcohol, and act upon a fresh 

 iodine preparation, it will determine a crystallization of iodine in situ, 

 and so fix the stain. Bine as well as brown staining preparations may be 

 so tested, but greater care is required with the preparations. 



Method for Studying Osseous Tissue. t — E. Rettererand A. Lelievre 

 first make paraffin sections of material previously fixed and decalcified. 

 Two methods of staining are given. In the first the sections are im- 

 mersed in alum-carmin for 12 to 24 hours, and then in potash-alum- 

 hsematoxylin ; they are then decolorized in dilute picro-hydrochloric acid, 

 and, after washing in running water, are dehydrated and mounted in 

 balsam. In the second method, the sections, with or without previous 

 mordanting in picro-hydrochloric acid, are treated for 24 hours with 

 potash-alum-hsernatoxylin, and then differentiated with the acid solution. 

 After a thorough washing in running water, they are overstained with 

 saturated aqueous solution of picric acid ; after a rapid wash in water 

 they are passed through alcohol, then xylol, and mounted in balsam. 



By these procedures it is found that the intercellular substance of 

 osseous tissue is composed of morphotic elements and an amorphous 

 mass. From a morphological and structural point of view, the authors 

 compare the fundamental substance of bone to reinforced concrete : 

 the iron framework corresponds to the capsules and to the trabecular 

 system of tnc bone, the cement or mortar to the amorphous and calcified 

 mass of the osseous tissue. 



(5) Mounting-, including- Slides, Preservative Fluids, etc. 



Fluid Mounting.} — C. E. Heath remarks that for fluid mounting 

 there is required a cement sufficiently hard to be adhesive, rigid enough 

 to bear handling, yet elastic, to stand the trifling differences of volume 

 due to temperature variation. Such a cement can be made as follows : 

 a penny tube of cycle-rubber solution, which is rubber in naphtha, is 

 emptied into a four-ounce bottle and double its volume of old gold- 

 size ardded, shaking till thoroughly mixed. This must now be placed on 

 a water- bath, or anywhere to be heated not beyond 150°, in order to 

 drive off the naphtha and any volatile constituent of the gold-size. 

 AVhilst this is being done, prepare a thick solution of shellac in abso- 

 lute alcohol (not methylated spirit) and add, when the other solution is 

 naphtha-free, twice its volume of shellac solution as thick as treacle. 

 Stir whilst hot and filter through line muslin before cooling It can be 

 thinned as desired with absolute alcohol. The reason why methylated 

 spirit cannot be used is that the denaturant which evaporates with the 



* Zeitscb. wiss. Mikrosk., xxvii. (1910) pp. 366-8. 

 t C.R. Soc Biol. Paris, lxx. (1911) pp. 630-3. 

 % Knowledge, xxxiv. (1911) p. 235. 



