86 THE AMERICAN MONTHLY [April, 



from a papilla at the bottom of the follicle. A sebaceous gland near 

 the top of the follicle secretes a sort of an oily substance which keeps the 

 hair glossy. A sweat gland is seen to the left of the hair — the gland 

 is simply a coil ; the duct ascends spirally to the surface of the skin. 

 Fat cells and fibrous tissue surround the hair roots. 



Slide No. 2, the w T ork of Dr. G. A. Marietta, of Clarion, Iowa, is 

 a section of Epithelioma, frozen and cut with razor, stained with 

 hsematoxylin, and mounted in balsam. No. 3, is by Frank French of 

 Lawrence, Kansas. Head of Gyrimis natator. 



Slide No. 4, by A. G. Field, M. D., Des Moines, Iowa, is transverse 

 section of 4 months' foetus. Cleaned in acetic acid and mounted un- 

 stained, in glycerine. " M. N. M." comments : 1, Harden your tissue 

 in alcohol. 2. Imbed in paraffine. 3. Cut with razor flooded with 

 alcohol. Don't bother about getting a section of the whole alimentai'y 

 tract, teeth and all, in a single section at first. 4. Stain with hsema- 

 toxylin. 5. Dehydrate with 95% alcohol. 6. Clarify with oil of cloves. 

 7. Mount in dammar. 



.Slide No. 5, by J. J. Davis, Racine, Wis., Section of Sarcomata., 

 hardened in 40, 60, 80, and 95% alcohol, imbedded in paraffine and cut 

 in a well microtome. " The Sarcomata are tumors composed of em- 

 bryonic tissue, connective tissue, classified according to size and shape 

 of cells. This specimen is of small round-celled sarcomata, the 

 special point of interest being presence of giant'cells, which are rare in 

 tumors of this kind, though common in those that spring from bone 

 medulla." 



No. 6, prepared by W. H. Walmsley, and contributed by G. M. 

 Houston, of Harrisonville, Mo. Transverse Sections of leaf and midrib 

 of Ficus elastica. Double stained and mounted in balsam. Artificial 

 light, and 1 inch and \ inch objectives recommended. 



Some Habits of the Crayfish. 



By Prof. Lf W. CHANEY, Jr. 



NORTHFIELD, MINN. 



To those who have followed the series of articles in this periodical 

 by Prof. Osborn on the histology of the crayfish, some memoranda of 

 my own concerning this handy arthropod may be of interest. In the 

 small river which runs by our town, and to which attention often turns 

 for biological material, the crayfish much abounds. The annual raids 

 to meet our demands do not seem in the least to decrease the supply. 

 It is a delight to the soul, whether aesthetically or biologically inclined, to 

 float down over the shallows and study through the clear water the 

 quaint lives of the aquatic animals and plants. 



■ The crayfish chooses the shady side of a rock and lies in wait. The 

 stalked eyes peer about with a comical twist, and if some savory morsel 

 comes floating along the claws begin to sway and reach with sluggish alert- 

 ness. The crayfish is by no means dainty and will consume any bit of 

 garbage which may come in his way. Like the sea-shore cogeners it 

 may be enticed and taken by a bit of meat tied to a string, and the en- 

 ticement is specially strong if the meat is tainted. It seems that an an- 

 imal provided with such a formidable armature would sometimes seize 

 living prey, but many observation have failed to show that it ever does 



