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PHOTOMICROGRAPH. 



STARCH. POTATO. MAGNIFICATION 

 200 DIAMETERS. 



cell wall in the early stage 

 of its development. 



Under the microscope 

 the granules show a charac- 

 teristic form and a struc- 

 ture composed of a series of 

 apparently concentric lay- 

 ers, which in connection 

 with the size and shape are 

 characteristic of the plant 

 to which they belong. 



The accompanying photo- 

 micrographs illustrate three 

 varieties. These were all 

 made at a magnification of 

 two hundred diameters, and 

 give an idea of the compar- 

 ative size, form and posi- 

 tion of hilum in these three 

 starches. 



The canna grains are well 

 known to microscopists as 

 "tous-les-mois," and are the 

 largest in common use. 



Starch Granules under 

 Polarized Light. 



BY PHILIP 0-GRAVELXE, SOUTH 

 ORANGE, NEW JERSEY. 



The microscopic exami- 

 nation of starch granules 

 under polarized light pre- 

 sents some advantages over 

 their examination in the or- 

 dinary way. 



With crossed Nichol 

 prisms giving a dark field, 

 the outline of the granules 

 may be seen to better ad- 

 vantage and the forms will 

 glow in the beautiful color 

 display afforded under po- 

 larized light. 



A dark cross is formed 

 with the place of intersec- 

 tion of its arms at the hi- 

 lum, the point at which the 

 grain was attached to the 



PHOTOMICROGRAPH. STARCH. BERMUDA ARROWROOI 

 MAGNIFICATION 200 DIAMETERS. 



