PRINCIPLES OF SEED TESTING 357 



genuineness, and high germinating power. Purity 

 may be taken to mean that the seeds composing the 

 sample consist of the variety required without admixture 

 of other seeds, or of sand, dirt, chaff, empty husks, &c. 

 Impurity is mainly caused by carelessness in separating 

 weed seeds from the bulk, and from want of care in 

 cleaning and screening, and is one of the most import- 

 ant considerations in purchasing seeds, as impure see'd 

 is the cause not merely of a diminished yield, but is 

 responsible for the spread of weeds. Farmers not 

 infrequently make use of the sweepings of hay lofts, 

 and thus encourage the reproduction of weeds, which, 

 later in the season, require much labour to be pre- 

 vented from choking the cultivated crop. . . . 



" In addition to a guarantee of purity, a high per- 

 centage of germination should be demanded, and the 

 germinating power of the seeds may usefully be tested 

 to see whether they come up to the standard named." 



According to the report of the Seed Control Station at 

 Zurich for 1908, no less than twenty-four British seeds- 

 men have their seed scientifically examined at that station 

 (Appendix V.). A glance at the catalogues of many of 

 our best seedsmen will convince the purchaser that 

 the seed sold by such business houses is eminently 

 satisfactory, since it is sold under guarantee and subject 

 to analysis by a recognised botanist. One or two 

 statements by firms may usefully be given here. In 

 the terms of guarantee of one firm it is stated that 

 their seeds offered in the list "have been carefully 

 grown, selected, cleaned, and repeatedly tested under 

 our personal superintendence. We are therefore able 

 to guarantee their analytical purity and high germina- 

 tion, and purchasers are invited to submit them imme- 

 diately to the analysis of any public botanist, and to 



