422 
REPORT OF CHEMICAL LABORATORY 
Inoculation 
Effect of 
temperature 
Tlie trees in the garden of Adam Afifi were tapped rather later than the others. 
This may account to some extent for the lower yield by the ordinary method of tapjjing 
as compared with those in the garden of Ali Nur-ed-Din. 
It appears evident from these figures that, at least as regards yield, the ordinary 
method of tapping offers a considerable advantage over that of simple gashing or the 
removal of shorter strips. Whether the life of the tree would be materially lengthened 
under the modified treatment could only he determined hv long experience, starting 
with virgin trees. As regards the quality of the gum, it may he noted here that the 
chemical examination of these samples failed to show any decided improvement as 
resulting from the altered method of tapping. 
InocidatioH. In view of the results of Clreig Smith’s investigations, which appear to 
prove that gum is formed as the result of infection of the sap by a microbe resident 
presumaljly in the hark, and also that extensive removal of the hark is undesirahle, an 
experiment was carried out as follows : Tapping was performed hy making a series of gashes 
with an axe, no hark being stripped off, and (as the chances of efficient natural inoculation 
might thus he lessened) an attempt was made to ensure the entrance of the microbe hy 
rubbing a moist rag over the Ijark and subsequently into the cut. .\ series of trees tapped 
in the native fashion (hy stripping the Ijark) was treated in the same manner for comparison. 
The following table exhibits the results obtained. 
Garden of 
Number of trees 
operated upon 
Size of trees 
Method of 
tapping 
Inoculated 
or not 
Yield of 
gum per tree 
Adam A fill 
■2:) 
Medium ... 
Ordiuary... 
.. Not inoculated ... 
0-9 rotl 
2.') 
„ 
• • }» •■ • 
Inoculated 
0-55 „ 
.. 
25 
„ 
.,' Short gashes 
.. Not inoculated ... 
0-28 „ 
25 
,, 
•• » 
Inoculated 
0-14 „ 
This quite unlocked for result is not without significance of practical value. It goes to 
show that the yield of gum is affected to a very great extent by conditions other than the 
mere stripping of the bark. The explanation of the lower yield may be that inoculation 
takes place ordinarily by the microbes falling upon the sap which exudes in slight quantity 
when the bark is stripped off, and that when the water was rubbed over the bark and then 
into the cut the effect was rather to wash away this sap and render inoculation less complete 
and effective. 
Ejfecf of teiHpe rdf lire. The above conclusions as to why the inoculation attempted was 
ineffective find sujjport to a certain extent in experience as to the effect of cold of fhe time 
if tapjii/iij. .\coording to the gum collectors, the trees should always be tapped on a warm 
day if a good yield of gum is to be secured. It is stated, further, that if the operation is 
performed on a cold day and several successive cold days follow, the tapping may lie nearly 
or quite fruitless. This statement finds confirmation in the results of the following 
experiments : — 
(iarden of 
j Method of Tapping 
'Cumber 
of 
Trees 
Temperature 
Average 
yield 
per tree 
Faki Wad Kullal 
1 
... Ordinary. No inoculation ... 
.2 
Hot day . 
1-.30 rotls 
1 
:) 
Cold day ... 
"•(!3 „ 
>1 
,, Attempted inoculation 
3 
Hot day ... 
0.45 „ 
J) 
n J? 
3 
Cold day ... 
0-16 „ 
