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the two lower sporangia. It is one cell thick, and the cells themselves 
are covered with spiral thickenings. According to Duval Jouve, these 
spirals are characteristic of all species of Equisetum except E. littorale 
and E. trachyodon. Figure 24 represents a section of a cone of E. 
hiemale, including parts of four sporangia. Owing to defective tech- 
nique, the spores are somewhat shrunken, but examination of fresh 
material, shows that all are spherical and all are uniform in size. 
Even in the section, the elaters appear clearly, and also the spirals in 
the walls. Figure 22 represents a single sporangium from a cone of 
E. variegatum var. Jesupi. Unfortunately the same shrinkage has 
taken place as in the cone of E. hiemale, but, despite that, it is evident 
that while some spores are normal in size, many are much smaller. 
The former always have elaters, while the latter often lack them. A 
further peculiarity is that the sporangium wall never has spirals. 
Through the kindness of the authorities at the Gray Herbarium of 
Harvard University, an opportunity was afforded to examine the 
cones of a number of specimens from eastern Canada and New 
England, including the type specimen from Royal ton, Vermont, and 
in all the same mixture of normal and abnormal spores was found. 
To sum up, E. variegatum var. Jesupi is like E. variegatum in the 
sheath with persistent teeth, in the location of the endodermis, in 
continuity of green parenchyma under the keels (rarely), and in 
absence of nodal organs in the rhizome. It is like E. hiemale in the 
black band of leaf sheath, and in the interruption of green parenchyma 
at both ridges and furrow^s (usually). It is intermediate between the 
two in height and diameter of stem, outline of ridges, relative size of 
vallecular and carinal canals, occurrence of tannin cells, and develop- 
ment of nodal periderm. Further, a large number of the spores are 
abortive, and the sporangium wall lacks spirals. 
Before considering the significance of these facts, it may be apposite 
to recall the conditions in another member of the same genus, E. lit- 
torale. According to Milde, this species is like E. arvense in the constant 
presence of two rows of canals, in the presence of tubercles, and often 
in the form and color of the sheath ; it is like E. limosum in the stomata, 
in the absence of a carinal furrow, in the teeth of the leaf sheath, and 
often in the form and color of the sheath. It is intermediate in the 
form of the green parenchyma which is sometimes like E. arvense and 
sometimes like E. limosum; in the cone axis which is neither hollow 
like the latter, nor entirely solid like the former; and in the central 
