CHAPTER III 



THE CARBOHYDRATES OF THE THALLOPHYTA AND 

 BRYOPHYTA IN RELATION TO PHOTOSYNTHESIS 



THE relationships of the carbohydrates of the angiosperm 

 leaf to one another are already known, though by no means 

 completely. At the present time, however, the question 

 of the first product of a carbohydrate nature to arise during 

 photosynthesis in the lower groups of plants has hardly 

 been seriously discussed at all. Yet it is a problem of 

 great interest, not only in itself, but also from a considera- 

 tion of the light it may be expected to throw upon the more 

 general discussion of carbohydrate synthesis and the func- 

 tions of the various members of this class. For in thallo- 

 phytes the distinction between assimilating and conducting 

 tissues is frequently a very indistinct one, and, indeed, is 

 sometimes non-existent. Accordingly, it is quite possible 

 that the disaccharides sucrose and maltose, which are the 

 forms in which sugars are most frequently translocated, 

 may be absent in some cases, and that starch may by the 

 action of a special type of diastase afford glucose only on 

 hydrolysis. For example, whilst ordinary malt diastase \ 

 generates dextrin, maltose, and glucose, by its action on ) 

 starch, taka-diastase, derived from the fungus Eurotium { 

 oryzce, hydrolyzes starch to maltose and glucose only, and j 

 from its mode of action has been shown to consist both of / 

 a diastase and maltase. Speculations of this type, how- 

 ever, are only useful in so far as they lead to the acquisi- 



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