986 DR THOMAS R. FRASER ON STROPHANTHUS HISPIDUS. 



the shaft ; and the long silky hairs that crown the summit of the stalk, the feather of 

 the arrow (Plate IV. fig. 6). 



The tuft of hairs forming the coma of the seeds has generally a conical outline, with 

 the apex of the cone pointing downwards ; and the summit of the tuft is usually dome- 

 shaped, but at times it has the form of a hollow cone. The hairs next to the seed proceed 

 from the stalk at an angle of about 70°, but higher up the stalk the angle gradually 

 becomes more acute, so that at the upper third it is about 40°, while at the further 

 extremity the hairs are nearly parallel with the axis of the stalk. 



In a few follicles the coma has been found to be nearly cylindrical in form, with all 

 the hairs placed nearly at right angles with the stalk. 



The dimensions and weights of the seeds vary greatly. 



Of twenty selected on account of their large size, the average length w r as 0'8 inch, 

 the average maximum width 0'156 inch, the average thickness from one flat surface to 

 the other 0*065 inch, and the average weight 0*78 grain. 



Of twenty selected on account of their small size, the average length was 0*5 grain, 

 the average maximum width 0*118 inch, the average thickness 0'058 inch, and the average 

 weight 015 grain. 



In order, if possible, to obtain a nearer approach to the average dimensions and weight 

 of the seeds, twenty were taken without selection from the seeds contained in the twenty 

 average-sized follicles from Buchanan, referred to at page 982, and it was found that the 

 average length was 0*686 inch, the average maximum width 0*143 inch, the average 

 thickness 0*083 inch, and the average weight 0*586 grain. These great variations are, 

 indeed, such as might have been anticipated in seeds obtained from plants in which, of 

 necessity, the conditions of maturity, season, and locality of growth could not be the 

 same. The averages which the figures represent cannot, therefore, be regarded as true 

 for all collections of seeds. This was further exemplified in the case of a large quantity 

 of seeds very liberally given to me in 1886 by Mr Mora, of the African Lakes Company, 

 of which twenty, likewise taken without any selection, had an average length of 0*7 inch, 

 an average maximum width of 0'16 inch, an average thickness of 0*088 inch, and an 

 average weight of 0'66 grain. 



It may, however, be stated that good mature seeds have a length of from 0*6 to 0*7 

 inch, and a maximum width of from 0*14 to 0*16 inch ; although they may be so large as 

 1 inch in length and 0*18 inch in maximum width. 



It is also difficult to define the average weight of the seeds. Deduced from the figures 

 in Table III., the average weight of each seed in the examined follicles of 1879 is 0'376 

 grain, in those of 1881 it is 0*379 grain, and in those of 1885, 0*403 grain ; and for the 

 collective follicles of these three years, 0*386 grain. The average weight, however, of each 

 seed in the largest follicle of 1879 is 0*57 grain, and in the smallest 0*27 grain; in the 

 largest follicle of 1881 it is 0*71 grain, and in the smallest 0*81 grain ; and in the largest 

 follicle of 1885 it is 0*71 grain, and in the smallest 0*22 grain (Table IV.). When these 

 figures are considered along with the circumstance that the average weight of each seed 



