1892.] MICROSCOPICAL JOUKNAL. 41 



Mounting opaque objects. — Use a piece ofpostal card covered with 

 colored tissue paper, laid under the slide, or on a B. and L. glass stage 

 under the slide carrier. This obviates making a back ground on tlie 

 slide tor opaque objects. 



To mount sand dry. — A tilni ot gelatine is placed on a slide with 

 asphalt centre after it has become thoroughly dried. Such slides may 

 be kept on hand ready for use. Breathe on the slide and cover with 

 dry sand, removing the excess. With the turn-table ring in a cell of 

 the hottest paraffine. As soon as the cell is deep enough to hold the 

 cover seal it down with parafRne and ring it with gold size. Use a 

 good quantity and touch both cover-glass and slide. When thoroughly 

 dry, ring it again. 



Confining living forms. — A bit of thin cloth (such as a veil) con- 

 tains so many meshes that it becomes practically a cage for small forms. 

 Silk bolting cloth is excellent, owing to the way it is woven, because it 

 retains its shape even when cut into small pieces and because it can be 

 obtained of any desired size. If the mesh is a trifle smaller than the 

 objective used, the captive cannot get out out of the field of vision. For 

 insects with antennie this will not answer, but another method is better. 

 Put the specimen with a verv small quantity of water in the glass of a 

 live-box. Lower the cover until it touches the drop. Then withdraw 

 it until a pool of sufficient diameter is formed. This pool being with- 

 out sides, there is no danger of injuring the specimens. If it is too 

 deep when reduced to the right diameter or if the water leaves the cover- 

 glass before it is sufficiently contracted, the quantity of water should be 

 reduced. 



Mounting Tubercle Bacilli. — In the rapid method of staining 

 tubercle bacilli, the sputum may be dried directly on the slide, and the 

 staining, decolorizing, and counter-staining may be performed on the 

 slide. Mount in Canada balsam or glycerine. This is more rapid than 

 the method in wdiich the sputum is placed on the cover-glass. 



Cements. — Do not buy cements in bottles with cork stoppers. In- 

 sist on glass stoppers. L^he cement will hold the cork fast to the bottle 

 after it has been out once and got soiled a little. The cork and your 

 patience will then be ruined. Vaseline placed on the stopper will re- 

 duce the tendencv to stickiness. 



BIOLOGICAL NOTES. 



Sweet Potato Blossoms. — A rare and interesting phenomenon, 

 that of a field of sweet potatoes being in full blossom in the fall, was re- 

 corded by Prof. Halsted in the last Torrey Bulletin. The field was 

 located in the southern part of New Jersey. 



An Insectivorous Plant. — At the Royal Gardens in Edinburgh is 

 a large insectivorous plant, of the genus Roridtda. The plant is a 

 native of Tasmania. It is a branching bush, with filiform leaves, 

 more slender than those of Drosera^ and, like the latter, furnished 

 with glandular hairs with which it captures flies. The glandular hairs 

 of the leaf of Z>rc».yc;-a will not move on contact with inorganic matter, 

 but they will contract upon a minute piece of fresh meat in the space 

 of twenty seconds. The insects most abundantly captured by Drosera 

 are ants. 



