134 OBSERVATIONS ON THE CALIFORNIA VINE DISEASE 
are very undersized and the vessels themselves fewer in number 
and subnormal; the phloems corresponding to these undersized 
wood fascicles are greatly reduced in size, free from bast-fiber 
bundles, which normally should be 2 or 3 in number, and covered 
with dwarfed pericycles. As one works towards the sides of the 
immature spots the wood fascicles increase in size and assume 
normal proportions; the phloem correspondingly increases in size, 
but the production of the bast fibers is slow, and at first frag- 
mentary ` the pericycles are soon of a size with those in matured 
tissue. There is no production of suber in the typical immature 
spot; it ends abruptly at the immediate edge of the matured 
tissues. With the production of the suber, if the cane is perfect, 
except for the immature spot, the bast fibers are produced 
normally. Starch is present in the matured tissues, but not in 
normal amount, if at all, in the immature spot. 
If we now examine in greater detail the modifications occurring 
in diseased canes, we will find that the above description applies 
only to those canes in which the immature spot occurs solely on 
shoots which are not only apparently but also morphologically 
matured. These canes are, however, rather the exception than 
the rule, and we find more frequently immaturity and morpho- 
logically imperfect maturity forming, to macroscopic vision, im- 
mature spots and maturity respectively. Furthermore, if one 
examines a sufficient number of canes, he will find that the 
immature spot is not morphologically constant: it may resemble 
more closely a morphologically matured cane than the cane, 
macroscopically speaking, on which it is found. I think it best, 
therefore, seeing the confusion that is liable to arise in the mind 
of the reader, to precede all further remarks by three comprehen- 
sive definitions: he will then know exactly what I mean when I 
speak of an immature spot; and my dual use of the term cane 
will not be ambiguous. 
C one (morphologically perfect).—Tissues exterior to the endo- 
dermis brown, dead; suber strongly developed; phloem normally 
developed; bast fibers never absent. 
Cane (morphologically imperfect).—Tissues exterior to the 
endodermis brown, dead ; suber well developed ; phloem perfectly. 
