ZOOLOGY AND BOTANY, MIOllOSCOPY, ETC. 151 



Technique of Bacteria.* — M. Kunstler reports that either the 

 vapour of osmic acid or the concentrated acid is a good fixing reagent for 

 Bacteria. To show the flagella of Spirillum tenue it is necessary to mix a 

 drop of osmic acid with a drop of the water containing the microbe, and 

 to allow of a quarter of an hour's evaporation. Having covered it with a 

 slip, a very small drop of a saturated solution of " noir Collin " is added 

 near the middle of the four sides. The preparation is then carefully 

 closed with wax, so as to prevent any evaporation. After some eight to 

 fifteen hours the Spirilla become intensely coloured, and the flagella may 

 be seen with moderate powers. At the extremity of the microbes there 

 are four to six flagella. If, in addition to the " noir Collin," we add a 

 little chromic acid, the body of Spirillum tenue presents a vacuolated, 

 reticular, or areolated structure ; the areolae often contain granules. 

 These appearances are best seen in specimens which are about to divide. 

 In the other process of reproduction, M. Kunstler thinks the term of 

 monosporous cysts to be preferable to that of spores. Good results are 

 got by the use of a concentrated solution of hematoxylin, to which a 

 little glycerin and chromic acid have been added. In some cases traces 

 of potash are preferable to chromic acid. 



(3) Cutting-, including Imbedding. 



Myrtle-wax Imbedding Process.j — Prof. W. H. Seaman says that 

 Mr. J. H. Blackburn, in attempting to carry out the Reeves process of 

 mounting,| failed entirely to get satisfactory results with what was sold 

 to him by the local druggists as myrtle-wax, which he desired to try 

 on the suggestion of Dr. Miller. On returning the wax, and stating that 

 there must be some other substance called myrtle-wax, he received an 

 article that gave perfect satisfaction, so much so, indeed, that he found it 

 better than paraffin, and substituted it for that. Having been furnished 

 with specimens, a short examination of its fusing point, &c, showed that 

 it was the Japan wax obtained from the Rhus succedanea, now an exten- 

 sive article of commerce. This substance is very peculiar in its great 

 latent heat, giving it a wide range between the fusing and solidifying 

 points. It solidifies without wrinkles, and sticks close to an imbedded 

 object, qualities that render it especially valuable to the section-cutter. 

 It is not strictly a wax at all, but a fat, since it consists chiefly of 

 palmitic acid, and is capable of saponification. Mr. Blackburn showed 

 whole brains saturated with it so perfectly, and preserved so naturally, 

 except colour, that there seemed no reason why they could not be 

 employed as models for class demonstration. To all appearances at the 

 present time they are permanent. The substance may easily be obtained 

 from the wholesale druggists. 



Homogeneous Paraflin.§ — Dr. G. A. Piersol says that much has 

 been written regarding the necessity of having paraffin of the right con- 

 sistence to insure success in cutting ribbon sections, but the desirability 

 of having it homogeneous has been but little emphasized. The selection 

 of a pure paraffin, freedom from turpentine or chloroform used in im- 

 bedding, and a very rapid cooling after the tissue is arranged, appear to 

 be the essential conditions for securing this desirable character to the 



* Compte3 Rendus, cv. (18S6) pp. 684-5. 

 t Queen's Micr. Bulletin, iv. (1887) pp. 33-4. 

 j See this Journal, 1887, p. 1048. 

 § Arner. Mon. Micr. Journ., viii. (1887) p. 155. 



