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nucellus stands free within a single integument and the 
latter is provided with a vascular system. On account of 
this Kershaw (79) made a comparison between the 
ovules of Myrica Gale and Trigonocarpus. Though 
this may be too far-fetched, it proves that there are 
indications, which make the homology of the integuments 
possible. 
For the present it has not yet been determined what 
the exact value of the integumental-units is. The synangial 
theory, mentioned in the introduction gives a possibility 
which is not to be rejected, but not to be wholly accepted 
either. More convincing proofs must be recorded than only 
a few resemblances as those between Lagenostoma and 
Telangium, observed by Miss Benson (15), and before 
her by Lang (84) between the 
micro- and mega-sporanges of 
Sfangeria. Î shall only mention 
some cases which may support 
this theory. 
It occurs occasionally that two 
nucelli are present in one integu- 
ment, which is observed for T'huya 
(49, p. 210), and which I have 
found twice in Ginkgo (fig. 12). 
Here it is possible that more 
Fig. 12. Ginkgo biloba; two sporanges of the original sorus, 
nucelli within one integument, in casu two, have developed, and 
sarcotesta with mucilage ca- 
nals, sclerotesta dotted stron- the others, remaining sterile have 
cr Den avi formed the integument. This is 
not a convincing argument at all, 
but this may be supplied, when more of these cases are 
published. 
In order to solve in short the questions put in the 
beginning, my conclusions are as follows: 
1. The integuments of the Pteridosperms and Gym- 
