333 The Microscope. 



4. Fresh muscle should be treated with alcohol, or osmie acid 

 (weak solution), and prepared in glycerine. When studying the 

 phenomena of contraction, the muscle should be examined either in 

 living insects or in recently removed parts immersed in blood serum 

 or some albuminous fluid (white of egg, e. g.), or in glycerine; but 

 never in water. 



In insect muscle preserved in spirit, especially if the insect has 

 been dropped while living into the spirit, the varying state of con- 

 traction of different elements of the same fiber may be seen just as 

 fixed at the time of death. 



5. Non-striped muscle. — Make a preparation of the mesentery 

 of newt or salamander in chromate of ammonia (5 per cent.), that is, 



§ j. of salt to § XX. aquse, and mount in glycerine. Double strain 

 with picro-carmine and logwood. To see the intercellular substance, 

 take a small longitudinally cut portion from the intestine and prepare 

 in chromate of ammonia and stain with logwood. 



Fresh preparations are made by teasing the muscle in glycerine 

 or Farrant's solution, after staining in logwood or eosin ; cover and 

 seal with Brown's cement or HoUis' glue. 



To show the intra- cellular network with gold chloride: 



(a) Dytiscus Maginalis. Decapitate a dytiscus; open the 

 thorax, remove a portion of a leg muscle and place in 1 per cent, 

 acetic acid for 5 to 15 seconds, then in gold chloride solution 1 per 

 cent, for 45 minutes, and leave in formic acid, 25 per cent., for 48 hrs. 

 in the dark; tease and mount in glycerine. 



(6) Bee. — Obtain a muscle from the thorax or leg of the 

 humble bee, prepare with acetic acid and gold chloride by the 

 method described; a network identical with that described in dytiscus 

 is shown. In order to obtain a muscle in as uncontracted a con- 

 dition as possible, gold preparations made from the leg muscles of a 

 bee, rendered insensible and immovable by chloroform vapor, are 

 the best. 



(c) Frog. — Fibers from the gastrocnemius, treated by the 

 Au. CI., method, yield an unmistakable network. 



(d) Lobster muscle treated with acetic acid and gold shows 

 the network in a most beautiful manner. 



(e) Rat. — Employ the same method as (d). 

 Acetic acid preparations ; 



Muscle fibers from the leg of a bee ; place in a dilute acetic acid 



solution 1 per cent, for from 5 to 15 seconds; then mount in glycerine. 



On examination they seem to present a transverse row of dots 



