8o 
Cor mack. — On a Cambial 
microspore. Nothing short of the discovery of undoubted 
seeds or germinated pollen-grains, in organic connection with 
these plants, would justify the assertion that they were 
spermaphytes or siphonogams ; and even granting them 
proved seed-bearing plants, their vegetative characters would 
then be so unique that, having regard to the result of Treub’s 
investigation of Casuarina 1 , it would be rash in the absence of 
such developmental evidence to include them in any known 
group of Spermaphytes. 
The results thus arrived at may be summarized as follows : — 
(1) A cambial activity exists in the nodes of modern 
Equisetaceae. 
(2) There is no evidence that secondary thickening was 
actually absent from any of the Calamitae. 
(3) The types of Calamitae whose structure is known, form 
a very closely-connected series in which the distinctions found 
in secondary tissues are such as might well be correlated with 
difference in bulk ; whatever be the systematic position of the 
Calamitae, they appear to form a united group. 
(4) The canal at the inner angle of each woody wedge of 
some Calamitae originates in the destruction of protoxylem, 
and is not due to loss of the phloem ; consequently it has the 
same origin as the carinal canals of Equisetaceae. 
(5) Cambial activity in Calamitae began in the nodes and 
thereafter extended to the internodes. In the nodes of living 
species of Equisetum a similar cambial activity is seen, which 
is less extensive and does not reach into the internodes. 
(6) Thus cambial activity in Equisetaceae and Calamitae is 
the same in essence, but different in extent. 
(7) Consequently the vegetative organs of the Calamitae 
present features which resemble those of the Equisetaceae 
more closely than has been admitted, while by this corre- 
spondence of structure the argument for classing Calamitae 
which show secondary thickening, among the Phanerogams, is 
effectually answered. 
1 Sur les Casuarinees et leur place dans le Systeme Naturel, Annales du Jardin 
Botanique de Buitenzorg, 1891. 
