748 APPENDIX. 



(2.) CAKBO-HYDEATES OK AMYLOIDS. 



Carbo-hydrates are bodies composed of six or twelve atoms of carbon 

 with hydrogen and oxygen, the two latter elements being in the propor- 

 tion to form water. 



Amyloses, C fl H 10 6 , Starch, Dextrin, Glycogen, Inulin, Cellulose, 

 Gum. 



Saccharoses, O ia H M O n , Saccharose, or Cane sugar, Lactose, Mal- 

 tose, Melitose. 



Glucoses, 6 H 13 6 , Dextrose or Grape sugar, Laevulose or Fruit- 

 sugar, Inosite, Mannitose. 



Of these the most important are: 



(A) Starch (0 6 H 10 B ) which is contained in nearly all plants, and 

 in many seeds, roots, stems, and some fruits. 



Characters. It is a soft, white powder composed of granules having 

 an organized structure, consisting of granulose (soluble in water) con- 

 tained in a coat of cellulose (insoluble in water); the shape and size of 

 the granules varying according to the source whence the starch has been 

 obtained. 



Tests. It is insoluble in cold water, in alcohol, and in ether; it is 

 soluble after boiling for some time, and may be filtered, in consequence 

 of the swelling up of the granulose, which bursts the cellulose coat, and 

 becoming free, is entirely dissolved in water. This solution is a solution 

 of soluble starch or am yd in. 



It gives a blue coloration with iodine, which disappears on heating 

 and returns on cooling. 



It is converted into dextrin and grape-sugar by diastase or by boil- 

 ing with dilute acids. 



(B) Glycogen. 



Glycogen, usually obtained from the livers, is also present to a con- 

 siderable extent in the muscles of very young animals. In order to 

 prepare it in considerable amount, it is best to use the liver of a rabbit. 

 The animal should be large, and should have been well fed on a diet of 

 grain and sugar for some days, or even weeks, previously. It should 

 have had a full meal of grain, carrots, and sugar, about two hours be- 

 fore it is killed, in order that it may be in full digestion. The rabbit is 

 killed either by decapitation, or by a blow on the head, and the abdo- 

 men is then rapidly opened, and the liver is torn out, is chopped up as 

 quickly as possible with the knife, and is thrown into boiling water. It 

 is important that this operation should be performed within half a 

 minute of the death of the animal, and that the water should not be al- 

 lowed to fall below the boiling point. The liver is to remain in the hot 

 water for five minutes; it is then poured into a mortar, and reduced to 

 a pulp, and is again boiled for ten minutes. The liquid is filtered, and 

 the filtrate is rapidly cooled. The albuminous substances in the cold 

 filtrate are precipitated by adding potassio-mercuric iodine and dilute hy- 



