146 The Plant World. 



studied bv him the amount of insoluble carbohydrates present 

 was greater in the red than in the green leaves. 



Since so much starch was found in the fallen leaves of 

 Liquidamher styraciflua similar material * was collected from 

 several other plants and the starch determined as above. Before 

 the starch was determined quantitatively many leaves were 

 sectioned and tested with iodine for starch. In most cases there 

 was a comparatively large amount of starch present as shown 

 by this test. 



The amount of substances present in the leaves capable of 

 reducing copper in Fehling's solution as determined by the above 

 method are shown in the following table : 



Liquidamber styraciflua 10. 79 % 



Ginkgo biloba 6 . 32% 



Platanus orientalis 11. 84% 



Platanus occidentalis 9 . 89% 



Styrax americana 5 .91% 



Magnolia obovata 7 . 19% 



Quercus pedunculata 14.54% 



Elaeagnus umbellata 10 . 24% 



It would not be possible without the use of special methods 

 of chemical analvsis to say what substances besides starch are 

 present in the material, that will reduce the copper in Fehling's 

 solution. There are other carbohydrates, such as pentosans, 

 which are hvdrolized by boiling in hydrochloric acid and which 

 reduce copper, that will be included along with starch. The 

 sugars, if any were present, were removed by washing the mater- 

 ial for several hours in alcohol and water. 



The above table shows that all plants studied contain an 

 appreciable amount of insoluble carbohydrates but with con- 

 siderable variation between the different plants. Such varia- 

 tions are not surprising. It is likely that the same plants 

 would show as great a variation if the material was collected at 

 a time when active assimilation was taking place. Meyerf found 

 that under normal conditions plants of different families varied 

 greatlv in the amount of starch produced, and in some cases 

 none was found, as for example, in many Liliaceae, Amarylli- 



*An material for these determinations was collected about 1 p. m. on a clear day. Care 

 was exercised to obtain specimens containing a large amount of chlorophyll but in practi 

 cally all cases some autumnal coloration was developed. 



tMeyer, A. Ueber die Assirailationsproducte der Laubblatter angiospermer Pflanzen. 

 Bot. Zeit. 43; 417. 1885. 



