ANATOMY OF THE CELL. a ty 
V. A form similar to the fourth, but the scalariform thick- 
enings are somewhat uregular. 
EXAMPLES: Reticulated ducts. 
VI. A modification of the fifth, but the thickened portion 
of surface is greater than that left thin, and the small thin 
portions are either circular or lens-shaped. 
EXAMPLES: Ducts with simple and bordered pores. 
Another class of cells, designed both for conduction of 
material and for support to the organ containing them, is 
By 
dfots 
Fie. 11. 
Cross-sections showing Collenchyma. A from stem of Chenopodium album. B from stem of 
Sambucus nigra. C from petiole of leaf of Nicotiana macrophylla. .D from stem of 
Ceratophyllum demersum. E from petiole of leaf of Phytolacca decandra. With the 
exception of B, the outer limits of the common walls may be seen. A and B x 200. 
C and E x 400. — (dAced. to Wiesner.) 
known as collenchyma. Cells of this class are generally 
longer in one direction than in the other two, and the thick- 
ening takes place along the corners or angles, leaving a narrow 
portion free for the transmission of contents. Such cells are 
found especially in portions of plants whose growth in length 
is not yet finished, while the six classes previously described 
belong to those parts where growth in length is ended. 
