FOREIGN MIXTURES IN SEEDS. 279 



The nature of the admixture is very different in 'different 

 cases. Only one of the many specifications fur^iished by 

 Nobbe is here transcribed. 



KED CLOVER. PEV. CENT. 



Genuine clover-seed 94, 56 



Foreign seeds -2.197 



Sand, &c 3.243 



The foreign seeds belonged to forty-four different species, 

 such as ox-eye daisy, or whiteweed, clover-dodder, medick, 

 plantain, sorrel, and five species of clover. The number of 

 weed-seeds was 30,123 to the kilogram (or about two pounds) 

 of clover-seed; or, as Nobbe most strikingly states it, "In 

 the clover-seed needed for an acre there would be furnished, 

 according to the sample, 1,300,000 seeds of weeds, or of 

 plants other than clover." Tlie author quotes the old 

 English proverb, — 



" One year's seeding is seven years' weeding." 



The detection of admixture of different varieties of the 

 same species, or of closely-allied species, is not an easy or 

 a gracious task, if, indeed, the former is at all practicable. 

 The discrimination between genuine seeds and most weed- 

 seeds is not difficult, particularly to a practised observer. 



The methods of determining the specific gravity of seeds 

 need not now be mentioned, for we must take up the sub- 

 ject of estimating their germinative power. For ascertain- 

 ing the latter, Nobbe employs an apparatus,^ which consists 

 of unbaked earthenware, with a channel for holding water, 

 and a disk for supporting the seeds. The earthenware disk 

 is kept sufficiently moist by the water around ; and by aid 

 of the cover, in which there is a thermometer, the tempera- 

 ture can be easily controlled. Near the supporting disk are 

 four large glass receptacles, which contain a strong solution 

 of potassic hydrate to absorb the evolved carbon-dioxide. 

 Upon the moist disk one hundred or two hundred seeds, 

 previously soaked, are placed, and the apparatus is kept at 

 the temperature of 65° or 70° Fahrenheit. On no account is 

 the disk to become dry. In a day or two, some of the seeds 

 will begin to germinate, and the number which have sprouted 



1 The specimen apparatus exhibited at the lecture was of the dimensions 

 recommended by Nobbe, — eight inches square and two inches high. 



