2 I I 
Some Peculiar Tyloses in Cucumis sativus. 
tubes be adhered to, we might also compare the wound-gum found 
surrounding the tyloses to the callus blocking up the sieve-plates in 
the autumn. The purpose of the gum would then be to prevent the 
stored water from being withdrawn into the vessels in the autumn 
and it would thus retain the water for the use of those parts of the 
plant near which it is stored. 
It has been impossible to confirm the suggestion put forward as 
to the function of the peculiar tyloses, as they were not observed 
until some time after the material had been collected in the 
ordinary way for laboratory purposes, and no further instance of 
such tyloses has been met with since then. Nor have we any 
information as to any special conditions which may have caused the 
production of these specialised tyloses. 
Owens College. 
July 31st , 1903 . 
EXPLANATION OF FIGURES ON PLATE X., ILLUSTRATING MISS- 
JORDAN’S PAPER “ON SOME PECULIAR TYLOSES IN THE STEM 
OF CUCUMIS SATIVUS .” 
Fig. !.—Transverse section of a large xylem vessel with pitted wall 
containing four lignified and pitted tyloses, a, b, c, d and several 
unlignified tyloses. The pitted walls of two wood parenchyma 
cells are shown. 
Fig. 2 .—Transverse section of a xylem vessel filled with thin-walled 
tyloses forming a pseudo-parenchymatons tissue. Three pitted 
wood parenchyma cells are shown. 
Fig. 3.—Part of a xylem vessel in transverse section containing two- 
tyloses covered by a gummy substance. 
Fig. 4. —Transverse section showing the connection between a lignified 
and pitted tylose and a cell adjoining the vessel. The pits have 
the appearance of a spiral thickening. 
Fig. 5.—Longitudinal section of a xylem vessel with pitted walls and 
the adjoining pitted wood parenchyma cells. The vessel contains 
five lignified and one thin-walled tylose and the connections- 
between the tyloses and the cells from which they arise are clearly 
seen. 
