272 BOARD OF AGRICULTURE. 



spoken of by Nageli^ as follows: "A third degree (of 

 partial sterility) is characterized by small, imperfect fruit, 

 and empty seeds; a fourth degree is marked by ordinary 

 fruit, and empty seeds : a fifth, by normal fruit, and ap- 

 parently good seeds which have no embryo ; a sixth yields 

 normal fi'uit, with seeds having a minute, imperfect em- 

 bryo, incapable of germination." Here are four sorts of 

 good-for-nothing seeds which might readily deceive. Of 

 course the degrees are very arbitrarily marked ; but they 

 serve to show, that, so far as external appearance goes, there 

 are bad seeds which might easily be mistaken for good ones. 

 The causes of such imperfect fertilization are numerous ; but 

 their consideration would take us too far out of our present 

 line of thought: it is enough now to call attention to the 

 fact that there are seeds, which, though apparently good, 

 are, through lack of a germ, far worse than useless. Their 

 false appearance of goodness is so deceptive, that it might 

 ordinarily escape detection. The detection of thes^ ex- 

 treme cases is possible, and will be treated of in the last 

 part of the present hour. When we speak of the estima- 

 tion of the value of seeds, it must not be forgotten that 

 seeds from the same plant may differ in inherited vigor in 

 all degrees, or very widely. 



3. Soundness. 



How far can a seed be injured by mechanical, physical, or 

 chemical agents, without being thereby killed, or even so far 

 impaired in vigor as to be undesirable for planting? The 

 practical bearings of this interesting question are very obvi- 

 ous. The inquiry has reference to depredations by insects, 

 and to the use of chemicals for the purpose of destroying 

 fungi in the coats of seeds. 



After Mechanical Injury. — Van Tieghem has published an 

 interesting account of certain researches made by him in 

 regard to the mutilation of seeds, by Avliich it appears that it 

 is possible to cut the germ of sunflower, for instance, into 

 separate parts, which will grow for a while, and which will 

 attain a considerable size. A vertical section divides a 

 plantlet into two lateral halves : each of these will grow, and 



1 Uastardbildung im Pflanzenreiche. Sitzungsb. der Math.-phys. Classe, 

 Konigl. Akad. Miinch. 1865, Dec. 15. 



