K CIA L ME THODS. 



209 



leaves especially are usually pretty deep yellow. This is 

 due to a pigment belonging to the group of lipochromes, 

 which is perhaps identical with xanthin (cf. Zimmermann 

 III 102). 



4. The Eye-spot. 



365. The name eye-spbt or stigma is given to the red or 

 brownish body observed in various motile Algae and swarm- 

 spores, which usually occur singly at the forward end of the 

 organism. These bodies correspond with the chromato- 

 phores in possessing a protoplasmic stroma filled with pig- 

 ment. This pigment appears, according to the investiga- 

 tions which have been made, to be identical with carotin 

 ( 170) in the green algae which have an eye-spot ; at least,. 

 it shows, according to Klebs (I, 30), the characteristic blue 

 color with sulphuric acid, in Euglena. 



The study of the eye-spot has heretofore been carried on 

 almost exclusively on living material. 



5. The Elaioplasts and Oil-bodies. 



366. Wakker gives (I, 475) the name elaioplasts or oil- 

 formers to bodies contained in the 



protoplasts, which he has observed 

 in the epidermis of young leaves 

 and in the superficial parts of young 

 stems and roots of Vanilla plan ifolia 

 (cf. Fig. 45, e). They consist of a 

 protoplasmic stroma and imbedded 

 oil. The latter is deeply stained by 

 alcannin ( 104) or cyanin ( no), 

 and escapes in drops from the elaio- 

 plasts when they are treated with an 

 aqueous solution of picric acid, 



. FIG. 45. Epidermal cell of a very 



With glacial aCetiC aCld, Or With COn- young leaf of Vanilla planifolia. 



e, elaioplast ; /, leucoplasts ; z, 

 Centrated Sulphuric aCld ; it IS SOlu- nucleus. After Wakker. 



ble in alcohol and in caustic potash solution. 



I have lately recognized elaioplasts in various other plant- 

 tissues, especially in the epidermis of different parts of the 



