Carbohydrate Production in the Higher Plants 7 
These biochemical characteristics, then, in the matter of their 
scatter, remind one of those morphological characteristics which are 
of secondary or tertiary importance rather than of the fundamental 
distinctions which hold without exceptions for large aggregates of 
families. 
For a last point we may take up the fundamental problem of 
whether a biochemical classification of plants is conceivably attain¬ 
able, given enormously increased knowledge. Assuming that all 
morphological as well as all metabolic features of plants must be 
the outcome of definable attributes of protoplasm, it seems clear that 
even if we could state these, we should still have the difficulty of 
balancing up conflicting affinities to decide phylogenetic relation¬ 
ship and that, as now, everything would turn upon consensus of 
evidence, before the biochemist could arrange his metabolic variants 
in families, genera, species and forms. 
We may well assume that the protoplasm of every form differs 
from that of every other in some particulars and that these differences, 
at the minimum, might be those of a set of systems composed of 
optical isomers. The richness of protoplasmic systems in proteins 
and carbohydrates would make far more stereo-isomeric variants 
possible than there are different living species and forms. On this 
basis plants would be classified by the configuration of their proto¬ 
plasmic atomic groupings in space, instead of by the configuration 
of their flowers and allied features. Ultramicroscopic form and mor¬ 
phology would replace macroscopic. 
A thorough-going attempt has been made recently to explore 
plant-protoplasmic activity to see whether such a conception of 
innumerable different stereo-isomeric protoplasms corresponds to 
anything in the actual facts of biochemistry. This laborious work 
has been undertaken by Reichert and the Carnegie Institution. 
After Reichert had shown that the haemoglobins of all animal- 
genera examined could be differentiated by crystallographic and other 
characters, so establishing a biochemical specificity of animal organ¬ 
isms, he decided to extend the same sort of enquiry into the plant 
kingdom. 
The substance selected was starch. His underlying conception 
was that branches of the protoplasm in amyloplasts responsible for 
the condensation of starch would probably possess slight stereo¬ 
chemical differences from species to species and that this must 
determine corresponding differences in the arrangement in space of 
