GERMINATION. 175 



important fact to keep constantly in mind is, that 

 when comparative germinating tests are made upon 

 seed of the same origin, the difference between the 

 results obtained should never be greater than 15 per 

 cent, after six days, nor more than 10 per cent, after 

 two weeks. The accuracy of these observations does 

 not depend alone upon the selection of the final average 

 sample, but also upon the germinator used; the layers 

 of seed, their respective positions, etc., are all factors 

 not to be overlooked. Long practical experience is 

 necessary before satisfactory restilts can be obtained, 

 and, if in the hands of a novice, the purchaser and 

 seller may both be at a disadvantage. For sprouting, 

 various mediums are used, of which may be mentioned: 

 Earth, peat, sawdust, paper, and various kinds of sand. 

 For an earth test it is desirable that the earth be of a 

 very light, sandy texture, one that will not cake on the 

 surface by repeated watering. 



The advantage of sand is, that it has always about 

 the same composition. Respecting this material, it 

 has been noticed that in comparative germination tests 

 with sand, the number of germs obtained 1515 per cent, 

 higher than in other mediums; hence, the importance 

 of the kind of germinating medium that is used. It is 

 desirable to use fresh sand for each test, or at least to 

 submit it to excessive heat in order to destroy all 

 germs.* The most simple of all germinators consists 

 of a receptacle containing sand saturated with water; 

 as the surface is, to a certain extent, hard, the seeds 

 remain in place when once in position. They should, 

 liowever, be sunk sufficiently in the medium to disap- 

 pear from sight. 



* There is a great difference of opinion as to whether seed retains 

 Its moisture during two weelis. Bretfeld says it does, while Knauer 

 shows that there is aloss of 2 per cent. In all sand germinators there 

 is always a difficulty in keeping the sand at a standard condition of 

 moisture, say 25 per cent. Knauer recommends that 200 grams— 140 

 c. m. sand, be placed in the apparatus ; after shaking, a perfectly hori- 

 zontal level is obtained ; 52 o. m, water are then added. 



