2426 Journal of Applied Microscopy 



0.3 per cent, of di-sodium phosphate (K2HPO4). A drop of this solution is 

 allowed to flow over a slide and cool. Fresh blood is spread on this cooled 

 layer and covered with a cover-glass. The blood elements including the plates 

 can then be observed alive under the microscope. F4xation is accomplished 

 by fumes of osmic acid, by the direct application of 1 per cent, osmic acid or 

 by Flemming's solution (II, A, 4). The fluid is allowed to flow under the cover- 

 glass, and at the end of five minutes the cover-glass is removed and stain 

 applied. Any (basic ?) aniHn dye gives good results, but haematoxylin alone or 

 with eosin is more permanent. This process shows the blood plates to contain 

 a nucleus with chromatin, sometimes in the form of a skein. This is best 

 shown by fixing with Flemming's solution and staining with methylen blue or 

 Heidenhain's iron haematoxylin. 



Dekhuyzen (1901) used 3 to 1 or 9 to 1 osmic and acetic acid (II, A. 9) 

 containing ^ per cent, methylen blue, and, if desired, a trace of acid fuchsin, 

 for fixing and staining blood plates. With invertebrates the acetic acid some- 

 times produces an objectionable precipitate of granular albumen ; then osmic 

 acid alone is used. Acetic acid has the objection that it decolorizes hemoglo- 

 bin ; with osmic acid this may with care be prevented. Osmic acid (9 to 1) 

 cooled on ice is considered particularly favorable for the demonstration of blood 

 plates in the blood of man and mammals. The pricked finger or ear is vigor- 

 ously stirred in the cold osmic-acetic. Dekhuyzen like Deetjen finds the blood 

 plates to be nucleated. 



Argutinsky (1901) recommends sublimate alcohol (II, B, 2, j) followed by 

 eosin-soda-methylen blue staining (III, D, 5, k) for demonstrating blood plates. 

 Well preserved plates are an intense red-violet, sharply outlined with a central 

 part and an outer pale, clear blue border. Ernest L. Walker. 



Massachusetts State Board of Health. 



Bacteriology for High Schools. 



Copyrighted. 



IV. 



MICROSCOPICAL EXAMINATION OF BACTERIA— Continued. 



Examination of Living Bacteria. A slide may be prepared for this purpose 

 by cutting a piece of blotting paper one inch square, and in the center cut a cir- 

 cular opening one-half inch in diameter. Place the piece of blotting paper on 

 a slide and moisten well with water. On another slide place a large drop of 

 water. From one of the colonies on the potato transfer to the drop a small 

 amount of the growth; mix well. On a cover glass place a very small drop of 

 this inoculated water. This drop should not be larger than the head of a pin. 

 The glass slide having the paper ring is inverted and lowered over the cover 

 glass, enclosing the drop. With a careful, quick movement the preparation is 

 brought right side up (Fig. 15). 



The diaphragm of the microscope should be nearly closed. Find the edge 



