224 PIGMENTS 



Meyer,* however, is opposed to these conchisions. A n'sjoiitf 

 of the literature on this subject is given by Miller,f who, work- 

 ing with the fruit of the sunflower, Helianthus an7iuus, finds 

 that very minute chloroplasts occur in the cotyledons of the 

 seed, and increase in size and divide by fission as germination 

 proceeds and maturity is reached. 



In green plants chlorophyll may occur not only wherever 

 light gains access to the living cells, but also in places where 

 light seemingly cannot penetrate, at any rate in any quantity, 

 for instance, in the cortex internal to the periderm — not only 

 in small twigs, but also of larger branches — in the medullary 

 rays and even in the pith.J Also it may occur in the cotyle- 

 dons of seeds before they are set free from the ovary or from 

 the cone ; Pimis, Euonymiis eiiropcEus, and species of Cucur- 

 bita are familiar examples. In some of these cases light no 

 doubt does penetrate through the walls of the superposed cells ; 

 this may be well seen if the seeds be removed and the lumen 

 of the fruit of the vegetable marrow be cleaned out. It is 

 hardly necessary to remark that if the chlorophyll in these 

 deeply-seated tissues be functional, its contributions to the 

 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,j| the seeds 

 of many Cucurbitacea^ 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 



* Meyer : " Ber. deut. bot. Gesells.," igii, 29, 158. See also Schmidt: 

 " Prog. Rei. Bot.," 1912, 4, 163. 



f Miller: "Ann. Bot.," 1910, 24, 693. 



J See Scott: "Ann. Bot.," 1907, 21, 437. 



§ Goldflus : " Rev. G6n. Bot.," 1901, 13, 49. 



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

 1909, 9, 27. 



