78 Journal of the Mitchell Society [September 



readily to, but does not stain, nor pass ])eyond the liprht line. The 

 light line is very much harder than other portions. Thej- have found 

 that while the outer portion of the seed is readily eaten by sul- 

 furic acid, the light line is not destroyed by it. The paper also 

 contains a very extensive list of the important literature. 



Some work has been done on the hereditary possibilities of hard- 

 ness. Harrington (8) gives an account of the tests on the experi- 

 mental farms, 1909-14. He says the percentage of hard seeds has 

 been as great from seeds when only 5 per cent were hard as from 

 seeds when 95 per cent had been hard. 



Hiltner and Kinzel (10) find that the percentage of hard seeds 

 is higher in some years than others, and that perhaps weather condi- 

 tions have an effect. They also find that rapid drying, 30° to 40*'C. 

 increases hardness. Harrington (8) and C'oe and ]\Iartin (3) have 

 not found a seasonal relation. 



Material and Methods 



All stages of development of garden peas and white sweet clover 

 seed coats, except those fully mature, were killed in chromoacetic 

 acid, imbedded, cut and finally stained with either safranin and 

 light green, or haematoxylin and safranin. ^Mature stages were taken 

 from free hand sections. In some cases the flowers were tripped and 

 age of seed figured from date of tripping, in other cases it is esti- 

 mated from the time the flower wilts Avhich is considered as the time 

 of fertilization. 



All microchemical work was done on fresh material grown in 

 the green house. The methods followed were those outlined by Zim- 

 mermann, Hass and Hill, and Tunmann. 



In this work hardness in peas was determined by soaking for 

 three days. Less than 1 per cent of most peas are hard. Some few. 

 however, appear to have hard seed coats, but admit water at the hilum, 

 as shown by swelling around that region first, as well as by stain- 

 ing. Sweet clover seeds were placed in gerrainator for 10 days and 

 those not swelled were considered hard. 



Development of Seed Coat 



These legumes have their seed coats made up almost entirely of 

 the outer integument. The inner integument in sweet clover never 



