ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 501 



following mixture : methylen-blue, '2 ; fuchsiii, • 8 ; carbolic acid, • 5 ; 

 glycerin, 40 ; distilled water, 20. This imparts a double stain and 

 shows the details well. 



The author has found the micro-organisms lie mentions more than a 

 hundred times in cases of undoubted cancer, and has frequently been led 

 to diagnose the condition in cases where malignant disease has not been, 

 suspected. 



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



Euparal, a New Mounting- Medium.* — G. Gilson finds that san- 

 darach, or pounce, a resin derived from CaJlitris quadriralvis, is a 

 valuable basis for mounting media. The principal menstruum is a mix- 

 ture of camphor and salol, called for short " camsal," which forms a 

 colourless liquid having a refractive index of 1* 58570. In this- 

 menstruum, sandarach is only slightly soluble, the addition of some 

 alcohol or other solvent being necessary. The two alcohols which were 

 found suitable for the purpose were isobutylic and propylic. The 

 mixture of sandarach, camsal, and propylic alcohol makes a medium, 

 having a refractive index of 1 •47892. 



Isobutylic alcohol was found to have properties more suitable for 

 microscopical technique ; thus it is extremely useful for dehydrating 

 delicate objects, and when used as solvent for camsal and sandarach, 

 forms a balsam having a refractive index of 1*47892. 



The two foregoing media have the inconvenient defect of dissolving 

 pigments, so that they are practically useless for mounting stained pre- 

 parations. In a mixture of eucalyptol and paraldehyde, the author 

 found an efficient substitute for the alcohols, and to the mixture of 

 sandarach and camsal with eucalyptol and paraldehyde, he gives the 

 name of " euparal." The refractive index of euparal is 1 '48302. 



Under the name of essence of euparal, Griibler supplies a mixture 

 for dissolving euparal. This essence is mixed with euparal in the pro- 

 portions of 1 : 1, or 2 : 1, and is useful in technique, as the preparations 

 can be taken directly from 70° alcohol to the medium. Euparal is-. 

 stated to possess all the qualities of an ideal mounting medium. 



Water-glass for Marking Slides-j — R. F. Griggs describes a 

 method for marking slides which is specially useful for serial sections. 

 The medium is water-glass, aqueous solution of sodium or potassium 

 silicate, thinned if necessary till it will flow well from a pen. A, 

 steel pen of the stub or ball-pointed sort is used. After the slides- 

 are marked they must be heated by holding them for a few seconds in 

 the blue cone of a Bunsen flame till the water-glass decomposes, giving 

 off strong jets of sodium light, and at the same time efl'ervescing so as 

 to leave behind a rough sandy surface. This is then rubbed down 

 against some hard object, such as a table edge. This leaves a ground- 

 glass surface, which will be unafl'ected by any reagent. If desired, 



* La Cellule, xxiii. (1906) pp. 425-32. 

 t Ohio Naturalist, vii. (1907) pp. 157-8. 



