72 American Quarterly Microscopical Journal. 



sulphuric ether to the water in which they are kept. Ether is a very 

 excellent quieting agent, as it mixes quite readily with water, it does 

 not sensibly affect the circulation, and the animals are as lively as ever 

 soon after being put back into fresh water. 



As was pointed out to me by my friend, L. O. Howard, a student in 

 natural history, the common caddis-worm, (one of the Phryganeidce), 

 shows the progressive contraction of the insect's heart most admirably. 

 If its continual up and down wave-like motion be overcome by put- 

 ting two or three drops of ether into the watch-glass of water contain- 

 ing it, it forms a most excellent subject for class demonstration. Lar- 

 val amphibians, quieted in the same way, show very well indeed the 

 action of the heart and the circulation in or through the gills. Doubt- 

 less, every microscopist will think of many other applications to make 

 of this valuable agent. 



2. Probably every teacher has experienced some disappointment in 

 attempting to show cilia and their motion to a class untrained in 

 microscopical observation. The demonstration may be made much 

 more striking and successful if a small quantity of blood is put upon 

 the slide with the epithelium. From seeing the large red corpuscles 

 whirled round and round the student is, naturally and easily, led to see 

 the cause. This is the same, in principle, as putting grains of carmine 

 upon the slide with the cilia, but is more striking and the blood is al- 

 ways at hand. 



3. On page 261, of Huxley and Martin's Elementary Biology, in 

 treating of the skin, it is stated that the mouths of the cutaneous 

 glands are seen as clear round spots, although their openings are really 

 tri-radiate. No directions are given for demonstrating that appearance, 

 but it may be done very nicely by putting a piece of skin from a frog's 

 back or side into MuUer's fluid one part, water, four parts, (any weak 

 solution of a chromium compound would do very well), for two or three 

 days. The layers of the epidermis come apart, and the external layer 

 shows perfectly the tri-radiate openings of the glands. If this layer be 

 colored in carmine or picro-carmine, it makes a very pretty and in- 

 structive object ; for it not only shows the mouths of the glands, but 

 the large flat nucleated epidermal cells. Prof. H. H. Straight, of the Os- 

 wego Normal School, says, " If a live frog be wiped dry with a cloth, 

 and then put into water over night, the external layer of epidermis 

 comes off very readily," that is, the frog has been made to cast its skin. 

 By making use of this process the points mentioned above might be 

 demonstrated without hurting the frog. 



4. A very easy way to keep dust, etc., out of watch-glasses, while 

 tissues are staining, or being otherwise prepared, is to cover them with 

 square pieces of glass. If it is desired to keep alcohol in watch-glasses, 

 with sections for several hours, evaporation may be prevented by 

 smearing the glass cover with glycerin. 



