CHAPTER I. 

 THE COMPOUND MICROSCOPE STRUCTURE OF STARCH. 



PRINCIPAL MATERIALS USED. 

 A fresh Potato. 

 Commercial potato-starch. 

 A bean ; or bean flour. 

 West Indian Arrow-root (Maranta). 

 Grains of Wheat. 

 Grains of Oat. 



Stem of the Sun-spurge (Eupliorbia lielioscopia) and of E. splendens or E. 

 Jacqiiin&flora. Fresh. (Other species can replace these if necessary.) 



PRINCIPAL REAGENTS USED. 



Potassium-iodide iodine solution (hereafter called simply "iodine solution ") 

 Alcohol iodine 5-0-10 per. cent, potash Diastase. 1 



Structure of the Compound ^Microscope. We will first become 

 acquainted with the separate parts of the compound microscope, 

 using as our typical instrument Beck's British Student's Micro- 

 scope, No. 54, referred to in the Introduction. 



In this microscope (Fig. 3) we can distinguish the solid 

 spreading tripod foot (F F F), the under bearing-surfaces of which 

 are in this case drilled, and cork inserted, so as to give a firm yet 

 elastic grip on the table. Upon this foot is hinged or jointed the 

 pillar (P), from which are supported the optical appliances of the 

 instrument, and which, by means of the joint, can be placed in an 

 inclined position, or thrown back to the horizontal. Projecting 

 from the front of the pillar, at about the level of the joint, is the 



1 The following reagents or materials are constantly in requisition ; hence 

 it is assumed that the worker always has them at hand, and they are not 

 mentioned in the chapter headings : A wash bottle of methylated alcohol 

 and another (or a tumbler) of water, absolute alcohol, glycerine, glycerine 

 jelly, potassium-iodide iodine solution (commonly called "iodine" in the text). 



1 



