li)0(>.] PUBLIC DOCUMENT — Xo. 33. 125 



From the preceding table it will be noted that there was 

 considerable more seed germinated in the aerated box than 

 in the unaerated one, as noted by the number of plants ob- 

 tained ; and that the average weight of the seedlings in the 

 aerated exceeded those in the unaerated by 46 per cent. 

 The seeds in the aerated box showed decided acceleration in 

 germination, there being a difference of at least thirty-six 

 hours in favor of the aerated seed. This experiment lasted 

 from October 5 to November 8, and the diff'erence in the 

 size of the plants became more marked each day. In the 

 aerated box the plants were noticeably larger over the funnel, 

 while in the unaerated box the plants were largest near the 

 edges of the box, where the soil had shrunk away from the 

 sides, which enabled the roots of the seedlings to have free 

 access to air. 



That oxygen plays an important part in the germination 

 of lettuce seed is quite evident from many experiments we 

 have made with this species. The mere fact of covering 

 lettuce seed loosely or sifting fine loam on them results fre- 

 <|uently in enormous differences in the germination. Such 

 seeds as lettuce and white clover are particularly susceptible 

 to aeration ; and, according to our numerous experiments, 

 these seeds germinate best in soils of loose texture. 



Comparison of Sterilized Loam and Subsoil. 



Some experiments were conducted two years ago by Mr. 

 S. R. Parker, then a senior specialist in the agricultural de- 

 partment of the college, which necessitated using a sterilized 

 soil. In all of Mr. Parker's cultures, which were made in 

 a soil very poor in organic matter, there was an extremely 

 poor and .sickly growth of soy bean in those pots which had 

 been sterilized, whereas the growth was good in pots which 

 had not been steamed. The experiments were carried on in 

 our ijreenhouse, and the results were so different from those 

 occurring in sterilized loam that it was considered wise to 

 repeat them. 



A soil similar to this had previously been sterilized for 

 the growth of tobacco seedlings, without producing similar 

 disastrous effects upon the plants. In the single experiment 



