VESTIGIAL AND RUDIMENTARY ORGANS IN PLANTS. ao 
VESTIGIAL AND RUDIMENTARY ORGANS IN 
PLANTS. 
By ALEXANDER Morron, B.A., B.Sc. 
(Read 7th July 1898.) 
SIMPLE unicellular plants like the green alga (Plewrococcus) 
exhibit physiological processes which are as complex as those 
of higher plants. This alga accomplishes within the minute 
limits of its cell-wall all those functions whose summation 
is termed life. As a consequence of the absorption of 
nutritive substances, the individual cell grows until it 
reaches a definite limit, when it divides into two daughter- 
cells. These daughter-cells repeat the same processes of 
growth and division in their life-cycle. Such unicellular 
plants have, in relation to their vital functions, been called 
polyergic, a term which implies that all the essential 
phenomena of life are compassed by the limits of a single 
cell. Multicellular plants in all probability arose from 
unicellular forms, and in this aspect it is noteworthy that 
all plants at one period of their existence consist of a single 
eell. The line which divides unicellular from multicellular 
plants is bridged by many intermediate forms which show 
by what course the evolution of thallophytes and cormo- 
phytic plants may have taken place. The colonies of 
Schizomycetes and Cyanophycee, and the plasmodia of the 
Myxomycetes, are instances of aggregates of unicellular plants. 
These colonial aggregates, however, show no integration of 
function; each unit of the colony is an _ independent 
organism. 
Spirogyra and Hydrodictyon are distinguished by the 
possession of a plant-body, which consists of an aggregate of 
cells whose walls are in contact with each other. The 
opportunity for subdivision of labour and function is now 
apparent. Yet the fact that a plant-body is formed in 
these two alge, has no influence on the life-history of these 
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