The Environment. 45 



tex and of the rubber contained in it renders the rubber unavailable in 

 the manufacture of the crude product or not. In order to answer this 

 question, a sufficient quantity of the debris was collected and subjected 

 to mastication. By this means it was possible to cause the partial agglom- 

 eration of the rubber, but it was quite impossible to separate out the 

 "bagasse" on account of the fineness of the particles. These have the 

 effect of separating the rubber so that it is in the form of a fine mesh- 

 work, the connecting isthmuses not appearing to be great enough to 

 overcome the surface-tension of the smaller masses. Microscopical ex- 

 amination shows the mass to be composed of minute fragments of tissue 

 derived from the wood and cortex embedded in the rubber. Measure- 

 ments of these particles showed them to be 0.02 to 0.1 mm. in size, occa- 

 sional pieces being as large as 0.5 mm. If during mastication one is 

 careful to allow only a small amount of saliva to bathe the mass, it may 

 be held together for some time, but if it be flooded for a moment and 

 worked meanwhile, it will quickly disintegrate and can not be reagglom- 

 erated. It therefore appears that the work of the beetle, while not destroy- 

 ing the rubber, puts it into such condition that it is lost to the manu- 

 facturer who uses a mechanical method of extraction, since the minute 

 particles can not be made to agglomerate. When the insects have once 

 got a fair start in a stack-yard the amount of damage which may be 

 caused in a short time by their very large numbers may be great enough 

 to warrant the adoption of means to avoid the loss, if it is found that 

 stacking the guayule is necessary. 



CROPPING BY GRAZING ANIMALS. 



It has been pointed out that the growing guayule is browsed by an- 

 imals. Burros, jack-rabbits, cotton-tails, and goats are all given to this, 

 and as these animals are numerous a great loss is entailed. Goats are 

 herded habitually in the guayule fields, and these animals, with their 

 all-devouring appetites, eat almost everything that grows. Not the least 

 damage done by them is the wholesale destruction of the developing 

 shoots and flower-buds, reducing the crop of seeds very greatly. Goats 

 and burros may, however, be pastured away from the guayule fields, and 

 thus loss may be avoided. 



The work of rabbits, where other food is available, is not serious, 

 though in the event of adopting forestry methods they may become a 

 menace to the plant. These marauders do not merely crop off the foliage 

 and new shoots; they lop off whole branches, which are left on the ground 

 to die. One jack-rabbit may therefore do a great deal more damage than 

 a goat in the same time. It has been noticed that they treat the gober 

 nadora in the same way. One frequently sees a complete circle of dead 

 branches about the base of a bush, all having been lopped off at one time. 



