112 



FRUITS 



that can be ascertained only by subjecting a transverse section to 

 examination under the microscope. 



The fruit has scarcely any odour or taste, but when to the crushed 

 fruit a solution of caustic potash is added a strong mouse-like odour 

 is developed. 



The student should observe 



(a) The glabrous surface, 



(b) The irregular crenate ridges, 



(c) The grooved endosperm, and, if possible, under the microscope, 



the absence of vittce ; 



FIG. 61. Hemlock fruit. A, side view of entire fruit. B, longitudinal section 

 of the same, showing endosperm and embryo, magnified 3 diam. D, half 

 of the same, further enlarged ; 3, embryo. C, transverse section : v, com- 

 missural surface ; /c, ridges ; 2, endosperm magnified 14 diam. E, portion 

 of the same, further enlarged; i, pericarp; r, seed-coat. (Berg.) 



and should compare the fruits with anise fruits, which are distinguished 

 by the short bristly hairs with which they are provided, by the presence 

 of numerous vittse, and by the endosperm, which is not grooved, the 

 latter being the most definite character visible under a lens. 



Constituents. The principal constituent of hemlock fruits is the 

 poisonous, volatile, liquid alkaloid coniine, of which they may contain, 

 when collected at the proper time and dried, as much as 2-77 per 

 cent. (Farr and Wright, 1904), the average being 1-65 per cent. This 

 alkaloid is the source of the strong odour produced when hemlock 

 fruits are crushed and mixed with caustic potash, the alkali liberating 

 the alkaloid which was previously combined with acids. 



The proportion of coniine present attains its maximum when the 

 fruits are full or nearly full grown, but before the colour changes 

 from green to yellow ; during this change (the ripening of the fruit) 



