2.VI TIIK A^IKUirAX MONTHLY [Sept., 



IxMus ;irr txiiiuiii lor iiu- study ol this rracliou. Willi the 

 point of a j^calpel, romovo a small (piantity, spread it on a cover 

 ^lass, and without allowinj: it to dry, separate the cells by gen- 

 tle blows with the side of the blade. The cells on the plate arc 

 then held over a wide mouthed bottle containing 1 or J <•. c , ol' 

 osniic acid. After 10 or 15 minutes, motnit in <i;lycerine and the 

 coloring will be more conspicuous as the cells are more com- 

 pletely separated. Having become familiar witli this reaction, 

 fat cflls may be rccoiznized in sections treated with this acid. 



SUiining with (piinoline blue is more elegant and more dilli- 

 cult. Add a few tlrops of a concentrated alcoholic solution to 

 a small vessel of water. Leave sections there till they are of a 

 deep blue, wa.sh rapidly and mount in glycerine. At the end 

 of24 hours the nuclei will be decolored, the protoj^lasm a clear 

 blue, the drops of fat appearing as intensely blue granules. 

 This color selection may be immediately produced by 4U per 

 cent potash solution (Ranvier). 



This connection of fat cells with one another and with the ves- 

 sels tnay be well studied in the omentum of the rabbit or of a 

 kitten. . . . Inject the vessels with Prussian blue, fix tlie 

 omentum with a bichromate solutioQ, remove a small piece and 

 let it partly dry as already described. Submit it to i)icro- 

 carmine for a few minutes, then, for at least 20 minutes, expose 

 to the o-jmic acid vapor. Fat is thus made insoluble, and the 

 I (reparation, after dehydration in alcohol and clearing by some 

 essential oil (berganiot), may be mounted in balsam. 



Another good stain for fat is made by macerating alcanet 

 root in 90° alcohol. Fix with bichromate, stain for about hall' 

 an hour, wash, mount in glycerine. All fat becomes red. 



TENDONS. 



For this study select the filiform tendons from the tail of a rat 

 where they form a unicpie bundle representing an exceedingly 

 simple tendon. They maybe easily and abundantly j)rocured 

 thus : — cut off the tail close to the body. With the fingers 

 break the end of the tail and ]iull it in tw-o, thus obtaining a bun- 

 dl«' of filiform tendons like a skein of thread ; keep for stu<ly. 



Endothelium. — After a rapid washing, puta few oftheselittle 

 tendons, into a solution of silver nitrate, 1 part to 500; place 

 the ves.xel in the sun and keej> the tendons constantly agitated. 

 When opalescent, wa«h in water, stain with alum carmine, wash 



