SECT. II. DISEASES. 01 



finding in one specimen a part of the ear uninjured, 

 I afterwards ascertained it to be. 



If this crust is not originally occasioned by the 

 puncture of insects, it is at least selected as afford- 

 ing a fit nidus for depositing their eggs. For in look- 

 ing at some specimens about a week after, I found 

 several in which the surface of the crust was dis- 

 figured with a sort of protuberant blister, which 

 when opened up was found to contain a maggot. 

 And even in unsheathing an ear which was thus 

 locked up and apparently inaccessible to insects, I 

 yet found a small black fly rummaging about in it. 



Sometimes the disease is occasioned from want 

 of an adequate supply of nourishment as derived 

 from the soil, in which the lower part of the plant 

 is the best supplied, while the upper part of it is 

 starved. Hence the top shoots decrease in size 

 every succeeding year, because a sufficient supply 

 of sap cannot be obtained to give them their pro- 

 per developement This is analogous to the pheno- 

 mena of animal life when the action of the heart 

 is too feeble to propel the blood through the whole 

 of the system. For then the extremities are always 

 the first to suffer. And perhaps it may account 

 also for the fact r that in bad soils and unfavourable 

 seasons, when the ear of Barley is not wholly per- 

 fected, yet a few of the lower grains are always 

 completely developed ;* which not only shows the 



* Smith's Introduction, p. 344. 



