404 POPULAR SCIENCE MONTHLY. 



sulphur washes. There has been very remarkable growth in the per- 

 fection of spraying appliances; pumps and dusters of many kinds are 

 upon the market. Particularly is the improvement in nozzles to be 

 noted. Nozzles constructed upon scientific principles, capable of 

 applying the liquid in the form of the finest spray to the tops of the 

 highest trees. In the place of the old hand pump and pail, we find 

 barrel pumps on wheels, tanks on wheels with pumps operated by 

 gearing attached to the wheels, and finally for the larger fruit farms 

 and for municipal care of shade trees are multiple pumps driven by 

 steam power. 



The treatment of seeds to kill adhering spores has been improved 

 upon in many details. It illustrates especially well the nature of the 

 development during the present epoch of plant pathology. Originally 

 the treatment for wheat smut was based purely upon superstition. Pliny, 

 for example, says that c if branches of laurel are fixed in the ground the 

 disease will pass from the field into the leaves of the laurel.' Tull in 

 1730 says that there are but two remedies proposed, brining and chan- 

 ging the seed. The avoidance of certain kinds of manure because of their 

 effect upon the host plant and because they carried the smut spores was 

 also advocated about that time. The scientific demonstration by Bref eld 

 that the plant is susceptible only when very small, gave rise to the 

 thought that by hastening the early growth the period of susceptibility 

 could be shortened, and methods of planting and tilling in accord with 

 that idea were advocated. In addition to cultural methods mechanical 

 treatment of seeds, such as passing the wheat loosely between millstones, 

 violent fanning, etc., were suggested about 1786. The chemical treat- 

 ment of seeds, says Tull, was accidentally discovered about 1660 by 

 the sinking of a shipload of wheat at Bristol, and afterwards, finding 

 it unfit for breadmaking, it was used for seed wheat. The following 

 harvest in England was very smutty except in the case of this acci- 

 dentally brined seed, which made a clean crop. Then followed brining 

 with liming and liming without brining, soaking in lime, arsenic, salt, 

 arsenic and lye, and various other treatments, none of which, however, 

 came into general use. Accident coupled with acumen again aided in 

 hastening a discovery. Provost while attempting to germinate some 

 spores placed some of them in water distilled in a copper vessel. These 

 failed to germinate, though similar spores placed in water which had 

 not touched copper germinated well. Following this lead he and 

 numerous other investigators experimented extensively with copper 

 compounds during succeeding years. 



Such is the history of the development of a treatment effective for 

 smut of wheat and barley, but not for that of oats. The next marked 

 advance was made by Jensen, a Dane, who in 1887 developed the 

 famous Jensen hot water treatment, a treatment which though re- 



