26 FIFTH REPORT OF THE ENTOMOLOGICAL COMMISSION. 
I 
(ill the course of the appearance of needles, and dwarfing the leading 
shoot) iheatking shoots, which, however, usually reach do great age, but 
arc provisionally of much importance to the life of the tree. 
The loss of increase in size resulting from disease is twofold. Some- 
times the shoots suffer in decrease in length, at others in shrinking in 
size. The diminution of length is shown after the year succeeding that in 
which the injury took place ; that in the terminal 
shoot of the branch, and especially the topmost 
shoot, the needles remain shorter. Not until 
later do they again assume their normal length. 
The fir also, whose topmost shoot is here repre- 
sented (Fig. 5), after injury received in the year 
1857 formed only short leading shoots, but in 
1861 again formed a strong shoot. 
The diminution of the growth in diameter is 
especially noticeable in the loss of the foliage or 
needles, which sometimes occurs in the year of 
injury, but more decidedly the following year. 
After a greater loss of leaves the annnal rings 
•lfcP>* •••••*'• "«>»l»« •■«'••• '••«••-. ••••■■.«»' ■" 
_■■■■•■»■ 
••■•■•■•■■■•a 
Fig. 6. 
Fig. 5. Terminal shoot of a 
fir defoliated by the nun-cat- 
erpillar in 1857, showing the 
different lengths of the 
year's growth. After Ratze- 
buvg. 
The last seven rings of pine stem almost wholly defoliated in. 
1858, but not killed outright. After Ratzeburg. 
are smaller and feebler, and this may sometimes 
last over for many years. (Fig. 6.) 
Nordlinger has repeatedly found signs of de- 
foliation by the May beetle for three years on 
oaks, also on Carya alba, in southern Germany, indicated by very small 
annual rings. 
The counting of the aunual rings to ascertain the age of the tree in 
the practically so important matter of discovering its rate of growth is 
rendered unsafe by the formation of double riugs, which may result 
from the sudden leaving-out in summer on young shoots, or by the co- 
alescence of two annual rings in one, aud sometimes even by the total 
omission of a ring. The sharply-defined difference between the spring 
and autumn growth of wood as denoted by the color, " white aud brown 
wood " of an annual ring, especially in the coniferous woods, enable 
them to be very easily counted, pr6vided there :s no interruption in the 
growth. In the deciduous trees the two layers of the aunual rings are 
