MICROSCOPIC OBJECTS. 29 



Fig. 57. Starch from Tapioca (Jatropha Manihot), x 350. 



The granules of this starch are chiefly remarkable for their 

 form, and the cross mark at the hihim being rather larger 

 than in most other starches, the hilum generally forming a 

 small black dot. The shape of these granules is also peculiar, 

 being convex at one end and plane at the other. 



Starches are best preserved dry when required for future 

 examination. 



Fig. 58. Starch from the Carrot (Daucus Carota), x 350. 



This starch has been drawn chiefly to illustrate the form of 

 the granules which are found in most of the flowering plants, 

 viz. the Exogens and Endogens. The form is generally glo- 

 bular, although other forms are occasionally found. The pre- 

 sence of these smaller starches is sometimes rather difficult 

 to determine, the iodine test being in this case superior to 

 the polariscope as a means of discovering them. They are 

 also very difficult to measure, many of them being of such 

 minute size that even the iodine fails to make them distinct 

 enough to measure with the micrometer. 



