SOUNDNESS OF SEEDS. 273 



produce a plant, but with much impaired vigor. Moreo^ er, 

 in other experiments the food in the seed-like fruit of " four- 

 o-clock," a garden-plant, was removed carefully, and replaced 

 by other starch, which the plant used almost as readily as 

 the uninjured ones did their own store of nourishment. 

 These striking experiments have been repeated, with more or 

 less success, at the Bussey Institution, by Mr. B. M. Watson, 

 jun. Similar observations have been made by Thaddaus 

 Blociszewski,' of whose results the following synopsis is 

 made : — 



1. The cotyledons of Piswn sativum (pea) and Lupinus 

 luteus (lupine) were severed from the radicle, and planted in 

 earth, and on moist paper. At the point of separation they 

 formed good roots, but no plantlet. 



If one cotyledon was left on, the plantlet was produced 

 about as soon, and as large, as in the case of uninjured seeds. 



Rye embryos separated from the food perished at once ; 

 but if they were cut vertically, and were allowed to use the 

 half food remaining, they thrived. 



Rye embryos did pretty well when separated from their 

 own endosperm, if they had access to a mixture of starch, 

 sugar, and asparagin. 



Injury produced by Physical Agents. — From the vast 

 amount of material respecting this subject, a selection has 

 been made from Professor Just's contribution in Cohn's Bei- 

 trage, 1877. It will be seen that the synopsis touches some 

 other points already alluded to. 



1. There is no fixed maximum temperature for the germi- 

 nation of the seed of any species. There are slight fluctua- 

 tions according to the peculiarities of individual seeds. 



2. By the action of a maximum temperature during germi- 

 nation, seeds suffer injury, which is expressed by an increase 

 of the time required for germination to begin, as well as by 

 a more tardy development of the germ. 



3. Sound seeds under normal favorable conditions for 

 germination start unequally ; that is to say, a small number 

 will start precociously, then the number rises rapidly until it 

 reaches a maximum, then gradually falls to the lowest point, 

 or zero. 



4. Seeds of the same species lose their vitality under the 



1 Landw. Jahrbiicher, 1876, 145-161. 

 35 



