118 THE AMERICAN BOTANIST 



use in fulling cloth, the sharp recurved and elastic bracts of 

 the flower-head being very useful in raising a nap on woolen 

 goods. The heads are fixed on a rapidly revolving wheel or 

 cylinder and the cloth passed over it m such a way that the 

 fibers are caught and shredded out. It is said that the in- 

 ventive genius of man has never devised an implement for 

 this work that could compare with this one of Nature's own 

 making. Most of the American teasels come from a small 

 region in Onondaga county, New York, where the industry 

 has been carried on for more than seventy years. Though 

 there seems to be no immediate danger that the demand for 

 teasels will cease, there is also little mducement for others to 

 embark in their cultivation because of the limited use. Since 

 the teasel is a biennial two years are required for one crop 

 and considerable hand labor is necessary especially in harvest- 

 ing and sorting. So nicely must the heads be arranged for 

 various classes of work, that they are often sorted into seventy 

 different sizes. An average crop will give 100,000 heads to 

 the acre which bring in market from fifty cents to two dollars 

 a thousand. 



Automobile Tires from Potatoes. — Few botanists ever 

 accjuire sufficient funds to put them in the class of those who 

 are annoyed by "tire trouble" and so are not directly interested 

 in the synthesis of rubber, but as plant students they may take 

 an aocademic interest in the matter. Many attempts have 

 been made to make artificial rubber, but only recently has the 

 task been accomplished. According to Scientific American 

 two German chemists have recently produced rubber equal in 

 all respects to natural rubber, starting with such unpromising 

 objects as potatoes. In the last step of producing rubber 

 synthetically, a hydrocarbon called isoprene is exposed to me- 

 tallic sodium and rubber results. All that remains, then, is 

 to find a cheap source of isoprene. This can be made from 

 starch of any kind, potate starch being as useful as any, Tak- 



