220 MASS. EXPERIMENT STATION BULLETIN 170. 



greatly, the tree often being completely girdled, and again only a local 

 effect is produced; i.e., portions of the tissue here and there will be af- 

 fected by the material. This results in relieving the tension of the tissue 

 at places, and an abnormal growth of the tissue follows. 



" Tanglefoot" appears to be the only substance that does not cause 

 injury when applied directly to the bark, i.e., when tarred or other heavy 

 paper is not used. Many laboratory samples of substances resembling 

 " Tanglefoot" have been made up, but in only one instance have any of 

 these materials resembled " Tanglefoot" in virtually all its properties; 

 at least, among those which have come to our notice. While the injuries 

 from banding substances have been quite pronounced, practically all of 

 the substances causing injury have now been discarded. 



An examination made by the writer of many trees treated with the 

 so-called "Tanglefoot" has revealed only one case of girdling, and even 

 in this case we were not able to obtain any clue to the jnanufacturer 

 of the particular material causing the injury. This substance, although 

 resembling "Tanglefoot," may have been one of its many imitations 

 some of which are known to cause injury. The only other case of injury 

 from "Tanglefoot" was where it had been applied to the trunk at the 

 same place for a number of years. The oil seemed to penetrate the outer 

 bark to some extent, affecting the texture of the bark; but this injury 

 is not serious, so far as we have observed, and can be prevented by chang- 

 ing the location of the band occasionally. We have never noticed any 

 injury from the use of "Tanglefoot" to the cortical tissue or cambium 

 located underneath the bark. Our previous experiments show that the 

 most delicate tissue was not injured when it was applied to various plants. 

 But injury was noticed to smooth bark trees when other banding sub- 

 stances were applied, even on tarred paper. Tarred paper alone is capable 

 of injuring the bark of some trees, and the injury mentioned above may 

 have been caused in this way in some cases. 



EFFECTS OF ILLUMINATING GAS ON TREES. 



A much larger number of trees suffer from the effects of escaping 

 illuminating gas in the soil than formerly. The increased death rate from 

 this cause may be accounted for by the fact that gas is now more exten- 

 sively used, and the larger pipes and different types of connections em- 

 ployed, together with the changes in the methods of laying and calking 

 the joints, also play their part; at least there is much less leakage from 

 small pipes having thread joint connections, which have been in the 

 ground for many years, than from larger pipes calked with oakum and 

 cement or lead. Electric cars, steam rollers, motor trucks and other heavy 

 traffic on highways are often responsible for defective joints and the 

 consequent leakage of gas, especially in newly installed lines. Also, the 

 continual undermining of gas conduits made necessary by the construction 

 of sewer and water lines, as well as the effects of frost in very cold winters, 



