11 



By the end of July or early in August the glands appear as small 

 cup-shaped structures, which become more and more filled with oily, 

 resinous contents as the season advances (Fig. A). The oily material 



i Young lupulin gland. 2 Section of the same. 3 Fully ripe gland. 

 4 Section of the same. 



is for a time transparent, of a clear golden-yellow colour resembling 

 amber varnish ; but when the glands are dead ripe the contents 

 become turbid or opaque, and look very much like particles of 

 " flowers " of sulphur. 



Hops are generally picked unripe, and even if allowed to ripen 

 the glands on being subjected to the drying process become 

 transparent again, so that in commercial samples they are always 

 transparent. 



The characteristic aroma of hops, the preserving effect they have 

 when added to beer, and the peculiar bitter taste which they impart 

 to the latter, are almost entirely due to the nature of the contents of 

 these glands. The aroma is chiefly due to a volatile essential oil, 

 while the preservative effect and bitter taste are associated with 

 various resinous substances dissolved in the oil. 



* The illustrations to this article are taken from the author's text book 

 on Agricultural Botany, by the kind permission of the publishers, Messrs. 

 Duckworth & Co., Covent Garden. 



