152 FOODS AND FOOD ADULTERANTS. 



prominent and common are the parenchyma, the sclerenchyraa, fibrous 

 tissue, and the fibro-vascular bundles. Spiral and dotted vessels are also 

 common in several of the adulterants, and in the epidermis other forms 

 of tissue which it is necessary to be well acquainted with though not 

 physiologically. The parenchyma is the most abundant tissue in all 

 material of vegetable origin, making up the largest proportion of the 

 main part of the plant. It is composed of thin-walled cells, which may 

 be recognized in the potato and in the interior of the stems of maize. 

 In the latter plant, also, the fibro-vascular system is well exemplified, 

 running as scattered bundles between the nodes or joints, and easily 

 made out. 



Fibrous tissue consists of elongated thick-walled cells or fibers which 

 are very common in the vegetable kingdom and are well illustrated in 

 flax. They are not as common in spices as in the adulterants. They 

 are optically active, and in the shorter forms somewhat resemble the 

 cells next described. They are seen in one of the coats of buckwheat 

 hulls and in the outer husk of the cocoanut. 



The sclerenchyma is found in the shells of many nuts and in one or 

 two of the spices. The cells are known as stone cells, from the great 

 thickening of their walls, and to them is due the hardness of the shell 

 of the cocoanut, the pits of the olive, &c. Their structure is illustrated 

 in Fig. 5 from Strasburger. 



FIG. 5. Sclerenchyma or stone cells. X 240. (After Strasburger.) 



Spiral and dotted vessels are common in woody tissue and are readily 

 recognized. . With all these forms the analyst should familiarize him- 

 self, and as an aid may consult Bessey's Botany in the American 

 Science Series. 



