1897] NORMAL AND DISEASED ORGANS OF ABIES BALSAMEA 343 
14. Fewer of the diseased scales have resin canals; more 
than two canals are never present. 
15. Epidermal hairs are rarely present on the diseased shoots. 
When present they are usually only one-celled. 
16. Resin vesicles begin to form even in the first and second 
year diseased shoots. They increase in size so that in five-year 
old branches vesicles or blisters are found 3 to 8™™ in diameter. 
In five-year old normal branches vesicles are never found more 
than 1™™" in diameter. 
17. Resin canals are always present in the wood of the 
tumor, and are nearly always present in the wood of older dis- 
eased branches above the tumor. The canals are usually found 
inthe spring wood. With the increase in age of the tumor, 
there is a corresponding decrease in the number of resin canals 
of the annual rings, but with the increase in age of the diseased 
branches an increase in the number of resin canals of the annual 
rings takes place. 
_ In conclusion, I wish to state that I am indebted to Director 
William Trelease and to the other officers of the Missouri Botan- 
ical Gardens for the use of their libraries and laboratories, and 
for kindly supplying facilities which have made it possible to do 
the work here presented. 
aes pues 
a 25 ea 
eae 
Missourt BoTaNIcaL GARDEN. 
EXPLANATION OF PLATES XIV AND XV. 
Fig. 1. Cross section of a normal leaf 4™" above its base, showing epi- 
dermal and hypodermal cells. 
_ Fig. 2. Cross section of a normal teak: showing the non-pitted, lignified 
: parenchyma of the pericycle, bounded on its dorsal side by the endodermis. 
Fig. 3. Cross section of a normal leaf, showing one of the two areas of 
transfusion tissue, 
bali 2 1G. 4. Cross section of a diseased leaf, 4™™ above its base, enn, the 
ae cee and hypodermal cells. 
= "IG. 5. Cross section of a diseased leaf, showing two areas of transfusion 
tissue: 4, non-pitted, lignified parenchyma; 4, bordered pits; s, simple pits. 
; IG. 6. Section of diseased leaf, showing non-pitted, lignified paren- 
‘chyma, Same magnification as in fig. 2. 
