Formation of Oil 149 



first place we must mention the eye-spot 40 observed in 

 many swarm-pores, and which, according to the opinion 

 of those investigators who have examined it more care- 

 fully, is probably a metamorphosed chromatophore, the 

 same as the chromatic bodies of the higher plants studied 

 by Arthur Meyer. 41 In the Euglenae its origin has been 

 more carefully studied by Klebs. Here it always origi- 

 nates by division, the organs being always preserved in 

 the resting cells. 42 It is not yet definitely decided whether 

 or not the pyrenoids in the chorophyll bodies of Spiro- 

 gyra and other algae are to be regarded as specially dif- 

 ferentiated parts of these organs. But it seems certain 

 that, at least in isolated cases, they multiply through di- 

 vision. 43 



On the origination of oil in plant-cells little i known 

 with certainty. Pfeffer has demonstrated that the oil 

 does not form in the vacuoles, but lies imbedded in the 

 granular plasm. Special organs which accumulate it 

 within themselves have lately been described by Wakker 

 for Vanilla planifolia, and have been called elaioplasts. 

 Although it has not been possible to find out their mode 

 of origin, the most natural assumption is that they are 

 metamorphosed chromatophores. 44 In some cases, as for 

 example in the diatomes, the oil-drops of the Algae evi- 



40 Cf. Zimmerman, Die Morphologic und Physiologic der Pflan- 

 zenzelle. p. 71. 1887. 



41 Meyer, Arthur, Das Clorophyllkorn. 1883. 



42 Klebs, Ueber die Organisation einiger Flagellatengruppen. 

 Unters. Bot. Inst. Tubingen. 1: 233. 



43 Schmitz, F. Die Chromotophoren der Algen. pp. 42 and 65. 

 1882. Schmitz, F. Beitrage zur Kentniss der Chromatophoren. 

 Jahrb. Wiss. Bot. 15: 142. 1884. Strasburger, E. Ueber Kern- und 

 Zelltheilung. p. 26. 1888. 



' 4t Wakker, J. H. De Elaioplast. Maandbl. v. Natuurwetensch. 

 No. 8. 1887. 



