CHLOROPLASTS 227 



food-stuffs of the plant, as Goldflus * has pointed out, must be 

 of considerable value. 



But in some cases the pigments of such chloroplasts may 

 not be the same as those of the ordinary chloroplasts of the 

 leaf; thus, according to Monteverde and Lubinenko/f the seeds 

 of many Cucurbitaceae contain not chlorophyll, as ordinarily 

 understood, but chlorophyllogen, which may pass over into 

 chlorophyll under the influence of light and some other factor, 

 possibly enzymic. 



Also it must be remembered that it does not follow that 

 because chlorophyll is present, photosynthesis necessarily takes 

 place, even though the requisite conditions, light and supply 

 of raw material, obtain. Thus it appears probable that the 

 chlorophyll in green parasites is not functional, and the same 

 holds for the chlorophyll in the gynaecium of certain plants, 

 e.g. Ornithogalum arabicum. At any rate, in these cases the 

 photosynthetic power is so small as to be masked by the 

 respiratory activity. 



Attention may here be drawn to the work of d' Arbamont, \ 

 who considers that the plastids containing chlorophyll may be 

 divided into two classes, chloroplasts and pseudochloroplasts. 

 Of these the former include those bodies usually termed chloro- 

 plasts, and are characterized by the fact that they do not swell 

 in water, and do not, as a rule, stain when treated with acid 

 aniline blue. On the other hand, pseudochloroplasts swell in 

 water and do stain with aniline blue. In some cases plants 

 may contain pseudochloroplasts only. 



With regard to the conditions necessary for the formation 

 of chlorophyll, light is the most important, but in addition a 

 certain degree of temperature, as well as the presence of certain 

 substances, such as iron and magnesium, are essential. There 

 is, however, some dispute regarding other factors. Palladin || 

 states that chlorophyll formation is an oxidative process, and, 

 as a result of his experiments, finds that etiolated leaves on 



* Goldflus : " Rev. Gen. Bot.," 1901, 13, 49. 



f Monteverde and Lubinenko : " Bull. Jard. Imp. Bot., St. Petersbourg," 

 1909, 9, 27. 



JD'Arbamont : " Ann. Sci. Nat. Bot.," 1909, 9, 197. 



See Belzung: id., 1891, 13, 17; " Journ. Bot.," 1895, 9, 67, 102. 



II Palladin : " Ber. deut. bot. Gesells.," 1891, 9, 194, 229; 1902, 2O, 224; 

 " Rev. Gen Bot.," 1897, 9, 385. 



I 5 * 



