116 ILLINOIS STATE ACADEMY OF SCIENCE 



1. Relation of Growth to Specific Gravity 

 of Seeds at 25 C. 

 a. Water Culture. 



Size. — A comparison of average values for the seedlings 

 grown in water, at temperature 25 °C can be most readily 

 obtained by a study of Tables 18 to 20; for the maximum 

 and minimum values, *Tables 1 to 17. 



An examination of the average values for the heights of 

 the shoots shows that the greatest and second greatest aver- 

 age heights of seedlings from seeds of each of the three 

 size groups are for seedlings from seeds of Density 1, 2 or 

 3. These average heights are graphically shown in Plate 

 I. In the hypocotyl and first internode no correlation be- 

 tween average length and specific gravity of seed is ap- 

 parent, but a direct relation does exist between these fac- 

 tors in the second and third internodes, in that, the lower 

 the density of the seed, the shorter the internodes. Fourth 

 internodes developed only in seedlings from seeds of Den- 

 sities 1 and 3. There is also a direct relation between aver- 

 age diameter of seedlings and specific gravity of the seeds ; 

 the seedlings from the denser seeds are larger in average 

 diameter than those from the less dense. 



In studying the maximum and minimum values of seed- 

 lings from seeds of the several densities, * Tables 1 to 17 

 are used. For the small seeds, the greatest shoot height is 

 that of a seedling from a seed of Density 5. The second 

 in height is from a seed of Density 3. For the medium 

 seeds, the three tallest seedlings of the series are from seeds 

 of Density 3. The two tallest seedlings from the large seeds 

 are of seeds of Density 2, the third tallest, from a seed of 

 Density 3. 



As in the case of the average length of hypocotyls and 

 first internodes so here, there exists no definite relation 

 between maximum lengths of seedlings of the different 

 groups and specific gravity of seed. In the second and third 

 internodes, the maximum lengths for the several series are 

 in every case, in seedlings from seeds of one of the three 

 highest densities. There is a marked difference between 

 the maximum lengths of these internodes in the seedlings 



