

ii 



54 SOME RECENT RESEARCHES IN PLANT PHYSIOLOGY 



tion of analytical data which have a direct bearing on the 

 subject. Researches with this end in view are at present 

 in progress in the laboratories of Trinity College, Dublin. 



Now, while it is quite possible that there is no one sugar 

 which is, in every class of plants, the first to arise during 

 photosynthesis, yet, since the intake of inorganic carbon is 

 a fundamental necessity, it is tempting to conceive of it as 

 following a uniform course. It may, therefore, be profit- 

 able to inquire into the nature of the carbohydrates occur- 

 ring in the lower groups with this idea in mind. For a full 

 summary the reader is referred to Czapek's " Biochemie 

 der Pflanzen." A good account of the chemistry of sea- 

 weeds is given in " Fertilizer Resources of the United 

 States." 



CARBOHYDRATES OF THE PILEOPHYCEJE. 



The recent investigations of Kylin (1913) have added 

 considerably to our knowledge of the algal carbohydrates. 

 To begin with, he proved that the brown algae Ascophyllum 

 nodosum and Fucus vesiculosus contain fructose. His data 

 for cupric reductions and polarimeter readings both before 

 and after inversion enable one to calculate the amount of 

 glucose present also, as well as that of a small amount of a 

 laevorotatory substance affording glucose on hydrolysis. 

 This is probably laminarin. 



Curiously enough, Kylin himself does not make any 

 calculation by the algebraic expression employed by Brown 

 and Morris, but attributes the discrepancy between the 

 calculations based on polarimeter readings and on titra- 

 tions with Fehling's solution as due to traces of fucosan, 

 though this difference varies from 0-14 to 1-09 per cent, 

 in terms of reducing hexose in the four algse he examined. 

 In Laminaria digitata and L. saccharina he records the 

 presence of glucose, but his readings prove that fructose 



