36 AQUATIC MICROSCOPY FOR BEGINNERS. 



easily made. With a triangular file cut one of the 

 smallest homceopathic phials in two, throw away the 



Fig. 3. — A Growing-slide. 



Upper half, and cement the lower to a little oblong or 

 square piece of ordinary glass or to a broken slip. At- 

 tach this to the slide by a drop of glycerine, taking 

 care not to use too much or the Square will glide out 

 of place when inclined. Fill the bottle with water, 

 coil- into it one end of a doubled, loosely twisted thread 

 of sewing-cotton, and place the other end in contact 

 with one side of the cover, as shown in Fig. 3. The 

 water will pass down the thread to one edge of the 

 cell, where it will flow under as it evaporates from the 

 other three sides. This usually works well, the secret 

 of success being to have the reservoir not more than 

 three-quarters of an inch from the cell, to keep it al- 

 ways full of wafer, and to have the doubled thread ap- 

 plied closely against the edge of the cover. If the 

 water-supply is too great, and the cell is therefore dis- 

 posed to overflow, shorten the end of the thread 

 against the cover; if not enough, lengthen the thread, 

 and do not allow it to touch the slide in its course 

 from the reservoir to the cell. 



Again, the observer will frequently want to make a 

 growing-cell of the slide on which he may accidentally 

 have placed a desirable or a beautiful object; that is, 

 he desires to preserve the specimen for several days in 



