CELL-CONTENTS AND CELL-WALLS. 79 



To prepare neutral olive oil, dissolve the oil in ether, shake it up 

 with dilu f e sodium carbonate, wash free from alkali, and evaporate 

 off the ether. In each of five test-tubes place 10 c.c. of water, then 

 add (1) 2 c.c. neutral olive oil ; (2) 2 c.c. neutral oil and 1 drop 

 10 per cent, caustic soda; (3) 2 c.c. neutral oil and 2 drops oleic 

 acid ; (4) 2 c.c. neutral oil, 2 drops oleic acid, 1 drop 8 per cent, 

 soda ; (5) 2 c.c. ordinary olive oil and 1 drop 8 per cent. soda. Shake 

 the tubes, place them in a stand, and note that only in (4) and (5) 

 is a permanent emulsion formed ; in the others, separation occurs 

 after a short time. 



87. Digestion and Translocation of Oils in Germination. 



Test both the cotyledons and the endosperm of dry Castor Oil 

 seeds with iodine : starch is absent. When the root and hypocotyl 

 have grown considerably, but the latter is still curved and the 

 cotyledons are embedded in the endosperm, remove the cotyledons 

 from the endosperm. 



Test for oil (osmic acid or alkanna), for starch (iodine), and for 

 sugar (Fehling), and note that the endosperm still contains only oil 

 and proteids ; abundant starch and sugar are present in the cortex 

 and pith of the upper portion of the hypocotyl, but the amount 

 diminishes further down and is there confined to the starch-sheath 

 (endodermis) around the bundle-ring ; in the root there is no starch, 

 but sugar is present, especially in the secondary roots ; in the 

 cotyledons (which before germination contain no starch), starch is 

 now present in the parenchyma cells around the veins, but oil also 

 occurs in the rest of the parenchyma tissue. 



As germination advances, the amount of starch increases in the 

 upper portion of the hypocotyl and in the cotyledons, and diminishes 

 as the hypocotyl elongates, until the development of these organs 

 is completed ; then both starch and sugar disappear from their 

 cells, having been used up in the process of respiration as well as 

 the formation of new cell-contents and cell- walls. 



88. Resins. Many ethereal or volatile oils consist of 

 solid oxygenated compounds dissolved in liquid hydro- 

 carbons called terpenes. Turpentine oil or spirit (ordinary 

 " turps"), which consists chiefly of a terpene (pinene), is 

 obtained from the volatile oil of various Conifers by dis- 

 tillation with steam, common resin ("rosin") being left 

 behind. Oil of camphor consists of solid camphor dis- 

 solved in a terpene. Most of the volatile oils are converted 

 by oxidation into more or less solid compounds called 

 resins or (if they still contain unaltered ethereal oils) 

 balsams (e.g. Canada balsam). 



