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On EMBRYONIC FISSION in PLANTS. 
By R. J. Harvey Grsson, M.A., F.R.S.E., F.L.8., 
LECTURER ON BOTANY IN UNIVERSITY COLLEGE, LIVERPOOL. 
With -Plate I. 
[Read 11th January, 1889.] _ 
L AM not aware that any one has hitherto suggested the 
possibility of the very general occurrence of embryonic 
fission amongst the Thallophyta, and although I have 
already drawn attention to this point in a paper published 
in a previous volume of this Society’s proceedings,* I 
think that the matter is of sufficient importance to warrant © 
further consideration. 
The phenomena of alternation of generation in plants 
are too well known to need detailed restatement here ; 
it may be noted, however, that where true alternation A 
generations occurs, the embryo, or product of the union of 
the ovum and the sperm, produces directly a plant which 
reproduces itself asexually, whilst the asexually produced 
spore arising from the sporophyte stage produces a gamo- 
phyte at once, or —- n sporophyte | generations have » 
intervened. 
In Adogonium fertilization is effected by a sperm fusing 
with an ovum (oosphere). The fertilized ovum or embryo 
(oospore) then undergoes segmentation like the ovum of 
an animal; but the segments, instead of uniting to form 
a single organism, separate from each other, and each of 
them gives rise to a new individual (swarm-spore) which 
after a period of free life becomes fixed and grows into the | 
* On the Terminology of the Reproductive Organs of Plants. Proce. Biol. 
Soc., L’pool, vol. ii. 

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