NOTES AND MEMORANDA. * 59 



use, in the treatment of wounds, oT pulverulents, styptics, balms, oint- 

 ments, caustics, camphor, iodine, alcohol, and a hundred other anti- 

 septic substances which act as barriers to the contact of Microbia, 

 or as agents of their destruction. Herein lies the principle of all 

 preservative and curative treatment. Medicine and hygiene is applied 

 to the destruction of the Microbia, external and internal, and to 

 augment the vital resisting power of the patient. 



The cultivation in fluids of Cohn, Eauliu, and Pasteur has shown 

 that certain species of Microbia (Aspergillus niger amongst others) 

 have never been found amongst the jDreparations impregnated by the 

 passage of a given quantity of air. Yet to procure this cryptogam it 

 suffices to expose a slice of moist bread to the air, when they are 

 soon seen to grow. This fact fully explains the variety of accidents 

 to wliich wounds may be subject by reason of the numberless modify- 

 ing circumstances which render them more or less amenable to the 

 development and increase of different Microbia." It would be very 

 desirable, he thinks, " to set up apparatus for analyzing the air in 

 hospitals by which the degree of salubrity or infection would be daily 

 determined." 



Orchella as a Staining Material. — Dr. C. Wedl, of Vienna, 

 describes the following process of staining animal tissues, in 

 Virchow's ' Archiv fiir Pathologische Anatomic,' vol. Ixxiv. p. 143. 

 The so-called French Orchclla-extract, from which the excess of 

 ammonia has been extracted by gentle warming in a sand-bath, is 

 poured into a mixture of 20 c, cm. absolute alcohol, 5 c. cm. con- 

 centrated acetic acid (of 1-070 spec, grav.), and 40 com. distilled 

 water, till a saturated dark-red stain is obtained, which must then be 

 once or twice filtered. Afler the section has been hardened in 

 Muller's fluid and spirits of wine or chromic acid, it is washed with 

 distilled water. The latter is then got rid of by means of blotting- 

 paper, and some drops of the staining fluid are applied to the section. 

 The stain is taken up immediately by the protoplasm of the cells, 

 whilst nuclei and nucleoli are not coloured. Horny or calcareous 

 epithelial formations likewise take no stain. Connective-tissue cells 

 are very deeply coloured, whilst the fibrillated intercellular substance 

 of the connective tissue takes less of the stain. The basic substance 

 of bones and that of the teeth take the stain, also the ganglion-cells 

 with their prolongations. Fresh pathological formations also give 

 sharp images when coloured with orchella. As medium the author 

 used levulose* 



Construction of Eye-pieces. —In consequence of the discrepancies 

 in j)ublished statements in regard to eye-pieces, Mr. W. H. Seaman, 

 of Washington, has made a full series of measurements of the parts of 

 eighteen eye-pieces by English and Continental makers. As the 

 result of these measurements (which were laid before the Indianapolis 

 Congress f), it was found that the common ratio between the focal 

 lengths of eye-lens and field-lens was \, in one instance it was ^, and 



* ' Zeitsclirift fiir Mikroskopie,' vol. i. p. 318. 

 t ' Ameiican Naturalist,' vol. xii. p. 838. 



