48 BOTANICAL GAZETTE [uty 
Doubt has been cast by BarLey (2) on THompson’s theory as to 
the origin of ray tracheids (7), on the ground that the roots used 
were probably wounded. With this criticism in mind, the material 
used in the present investigation has been carefully examined for 
evidences of wounds, Though the possibility of such is not denied, 
it may be said that the soundest and straightest pieces were selected 
for study, and no indications of wounds were seen in the sections. 
It may be fairly considered that the relation of erect cells to sieve 
tubes is established, first because of the occurrence in primitive 
regions of the plant of erect cells so greatly elongated as to be 
eight times as long as wide, secondly because of their containing 
much protoplasm but no starch, thirdly because they possess sieve 
pores, fourthly because they eventually lose their contents and 
collapse, frequently after the nucleus has divided amitotically. In 
all of these respects they resemble sieve tubes. To this may be 
added that they are sometimes cut off from the end of a sieve tube. 
They are in fact sieve tubes except for possession or rather retention 
of a nucleus, for the matter of length is 4 minor one in view of the 
occurrence in the young root of much elongated erect cells, and the 
great variation in length of sieve tubes in mature plants of different 
i tihaaind short tubes occurring for instance in the classic case of 
Cucurbita. 
young parts of the plant, i 
among radial rows of siev. 

