LABORATORY EXERCISES. 471 



twenty-four hours. The resulting solution contains the myosin. 

 Note the readiness with which myosin coagulates by diluting a few 

 c.c. of the solution with water, and by adding finely powdered salt 

 to the solution and stirring. Boil a few c.c. of the solution, filter, 

 and examine the filtrate for calcium salts by adding ammonium 

 oxalate. 



2. Prepare muscle-plasma and isolate the myogen from this as 

 described on page 366. Examine the resulting product. 



3. Demonstrate the presence of glycogen in fresh muscle-tissue 

 (page 374). 



4. Demonstrate the presence of glucose (page 375). 



5. Demonstrate the presence of lactic acid (using about 100 

 grammes of meat) (page 377). 



6. Demonstrate the presence of kreatin (page 380). 



7. To demonstrate the xanthin bases it is most convenient to start 

 with a meat extract, for example, with 100 grammes of Liebig's 

 extract. Proceed with this as described on page 381. 



Exercise XLIII. 1. Isolate protagon from a fresh calf's brain 

 (page 391). 



2. Demonstrate the presence of lecithins in the brain (page 393). 



Exercise XLIV. 1. Decalcify pieces of bone with 50 per cent, 

 hydrochloric acid ; let stand from twenty-four to forty-eight hours. 

 Decant the acid solution which contains the mineral constituents. 

 Wash the remaining ossein with water and with dilute soda solution, 

 then place in a bowl with water and boil until the ossein has dis- 

 solved, neutralize or make faintly alkaline with soda, decant, and 

 cool ; note that the solution jellies (gelatin). 



2. From cartilage-shavings isolate the chondromucoid (page 404). 



Exercise XLV. 1. Demonstrate the presence of iron-containing 

 albuminates in the liver (page 423). Use about 100 grammes of 

 tissue. 



2. Feed a rabbit about 25 grammes of glucose through a tube ; 

 kill it several hours later, and demonstrate the presence of glycogen 

 in the liver (page 425) ; use a portion of the same liver for the 

 following experiment : 



3. The demonstration of glucose (page 425). 



Exercise XL VI. Prepare guanylic acid from pancreas as de- 

 scribed on page 426. 



Exercise XL VII. 1. Note the general physical properties of 

 milk ; examine a drop microscopically ; note the reaction and the 

 specific gravity ; boil some milk. 



2. Isolate the different albumins of the milk (page 436). 



3. Estimate the total albumins (page 436). 



4. Add some essence of pepsin (rennin) to milk ; place in the 

 incubator at 40 C. and note the occurrence of coagulation (page 

 434). 



5. Let a specimen of milk stand exposed to the air for forty-eight 

 hours ; note the reaction. What has occurred ? (Page 434.) 



