110 FRUITS 



mericarp. Very many Umbelliferous fruits contain six vittse, but 

 some contain more (anise) , whilst others contain none at all (hemlock) . 

 They are generally best seen in transverse section under a strong 

 lens, when they appear as dark brown minute spots or cavities (compare 

 fennel, hi which they are conspicuous). 



The transverse section exhibits also a narrow pericarp and a large 

 oily endosperm, the commissural surface of which is not grooved. 

 The small embryo lies near the apex of the fruit. (Compare 

 fig. 59.) 



Caraways exhale, when crushed, an agreeable aromatic odour, and 

 possess a pleasant aromatic taste. 



The student should observe 



(a) The glabrous surface of the fruit, 



(6) The si% vitice on the transverse section, 



(c) The endosperm, which is not grooved. 



Constituents. Caraways yield by distillation from 3*5 to 7'0 per 

 cent, of volatile oil, the principal constituent of which is carvone 

 (50 to 60 per cent.). They also contain fixed oil (in the endosperm) 

 and yield about 6 (not over 9) per cent, of ash. 



The volatile oil should have a sp. gr. 0-910 to 0-920 and O.K. -f 75 to + 82 ; 

 at least 50 per cent, should distil at a temperature over 200. Oil from which 

 part of the carvone has been removed ( ' decarvolised ' oil) has a lower sp. gr. 

 lower optical rotation, and yields less than 50 per cent, boiling above 200. 



Varieties. Dutch : Holland produces and exports far larger 

 quantities of caraways than any other country ; they are of medium 

 size, dark colour, and clean appearance, and yield from 4-0 to 6-5 

 per cent, of oil. 



English : these are produced in small quantity only ; they are 

 similar to the Dutch but brighter in colour. 



Adulteration. Caraways and other Umbelliferous fruits used in 

 the production of volatile oil are distilled either ground or entire ; 

 in the former case the yield is increased, and the exhausted fruits are 

 used as cattle food ; entire fruits yield less oil, and the exhausted 

 drug after drying may be mixed with the genuine fruits. These 

 exhausted fruits may be recognised by their dark colour, deficiency in 

 aroma, and low yield of aqueous extract ; they often also sink at 

 once in water (fennel), whereas the genuine float for a considerable 

 time. 



Uses. Caraways, or the volatile oil obtained from them, are 

 extensively used as an aromatic carminative. 



