PICEA SITCHENSIS, THE MENZIES SPRUCE. 265 
a callus formation. Figure 1 shows a cankered portion with the 
split bark on a three-year-old stem. Figures 3 and 4 show a 
characteristically cankered stem from both sides. The plastic 
material coming from the whorl branches nourishes the living 
tissues and stimulates callus formation where splitting has taken 
place, and this results in the swollen portions (very well seen in 
Figure 4) at the base of the living branches. 
An anatomical examination of the tissues leaves little doubt 
that frost is the primary cause. Dead branches were only found 
on trees which showed canker, and the canker seems to occur 
invariably lower down on the tree where the parts are two or 
more years old. 
The fructifications of an ascomycetous fungus are invariably 
present, and this may have something to do with the malady, 
but it will require further investigation to settle this point. 
The appearance of the fungus fructifications dotted over the 
surface of the stem above the whorl of branches is seen in 
Figure 2 
Apparently other conifers have been attacked in a similar 
way. Early in October Mr. Leven, head forester to Mr. Oswald 
of Auchincruive, Ayrshire, and a former member of the staff of 
the Royal Botanic Garden, sent a branch of Douglas fir which 
shows the fructifications (apothecia) of an ascomycete apparently 
similar in every way to those on the Menzies spruce and, as will 
e seen from the photograph of this specimen, Figure 5, the 
splitting of the stem with the subsequent callus formation 
agrees exactly with what takes place in the Menzies spruce. 
Quite recently I have seen in Perthshire many young Douglas 
firs, and also a specimen of Abies nobilis, which showed identical 
symptoms to those above described. 
EXPLANATION OF THE FIGURES IN PLATE LI. 
Illustrating Dr. Borthwick’s paper on ‘‘ Frost Canker of 
Picea sitchensis, the Menzies Spruce.” 
Fic. 1. Apical JE of young Menzies spruce, showing the dead leader replaced 
branch, and also, below it, the cankered portion of stem. 
Fic. 2. Portion of a showing the fructifications of an ascomycetous fungus. 
Fic. 3. Portion of a cankered stem showing splits in bark with subsequent callus 
formation and swellings below the branch whorls. 
Fic. 4. The same same specimen as in Fig. 3, but seen from the opposite side. 
Fic. 5. Branch of Douglas fir, showing symptoms similar to those in Menzies spruce. 
