2 
F. F. Blackman 
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THE BIOCHEMISTRY OF CARBOHYDRATE 
PRODUCTION IN THE HIGHER PLANTS 
FROM THE POINT OF VIEW OF SYSTEM¬ 
ATIC RELATIONSHIP 
A CONTRIBUTION TO THE DISCUSSION ON BIOCHEMICAL CLASSIFICATION OF 
PLANTS AT THE CARDIFF MEETING OF THE BRITISH ASSOCIATION 
By F. F. BLACKMAN 
I n surveying the Carbohydrate Economy of Flowering Plants as 
a whole, we note that there is a general uniformity, interspersed 
with some strikingly aberrant cases. These exceptional cases are not 
distributed indiscriminately, but tend to characterize groups of 
plants which are classed as related systematically, which we interpret 
in terms of common phyletic origin. The attempt of the present con¬ 
tribution is to review some of these biochemical diversities of carbo¬ 
hydrate production and see what they look like as steps toward a 
biochemical classification of plants, and how they rank with the 
morphological characters on which groups of flowering plants have 
been mostly drawn up. 
Carbohydrate production can b& analysed into three strata, 
representing progressive stages of what we may call the up-grade 
carbohydrate flux. 
We have (1) the primary photo-reduction of carbonic acid in¬ 
volving light-energy and specific pigments: (2) the immediate appear¬ 
ance of sugars; which seems to be universal: (3) the subsequent 
appearance, though by no means universally, of complex poly¬ 
saccharides, which are deposited in the chloroplasts. Similar bodies 
are also formed in the leucoplasts of storage organs from sugars 
arriving from the leaf by translocation. 
These three stages represent increasing chemical condensation to 
larger and larger aggregates. The first stage, derived from reduction 
