24 THE CHOCOLATE-PLANT: 



ment-cells, and ducts with spiral markings. The starch grains 

 do not have any very characteristic form or markings : they are 

 generally spherical and simple. The only peculiarity worth men- 

 tioning, is the relative slowness with which they are acted on by 

 hot water and by iodine. The coloring substances are mainly of 

 a carmine or violet color, and are distinguished by the change of 

 shade when an alkali is added, becoming thereby darker. 



These are the only structural elements which a pure powder 

 or paste of chocolate should show under the microscope. Any 

 other substances must be recognized as accidental or intentional 

 additions. 



All seeds of whatever kind contain, as a part of their substance, 

 the matter of which cell-walls are made ; namely, cellulose. The 

 percentage differs in different seeds, in those of the chocolate- 

 plant being about three in the hundred. Cellulose has the same 

 chemical composition as starch ; but its physical properties are not 

 the same as those of starch, among which may be mentioned its 

 entire insolubility in boiling water. 



Starch forms, on an average, eight to ten per cent of chocolate- 

 seeds. It consists of minute spherical grains, not distinguishable 

 from that found in many other kinds of seeds. Traces of gum 

 and of other allied bodies are also present in the seeds. 



Albuminoids, or substances resembling, in a general way, the 

 albumin of egg, occur in chocolate-seeds as they do in other seeds, 

 and in a somewhat higher amount than in certain other cases in 

 which the seeds are used as food. The percentage ranges from 

 about fifteen to twenty, depending on the variety. These albumin- 

 oids are compounds of nitrogen, and are extremely nutritious. In 

 the seeds they occur in a readily assimilable form, fit for digestion. 

 Their peculiar relations as flesh-formers are referred to in the 

 section treating of the physiology of chocolate-seeds. 



