250 DR J. M. MACFARLANE ON THE 



paratively delicate epidermis. Is it possible, one may ask, to obtain an equally balanced 

 morphological and physiological blending of such leaf peculiarities ? In other words, were 

 the hybrid exactly intermediate morphologically, would it be able to carry on efficiently 

 its physiological work ? To be in a position to answer this we would require — what is 

 still a desideratum — accurate statistics as to (a) the amount of transpiration from 

 stomata on the upper as compared with those on the under leaf surface ; (b) the effect on 

 elaboration and transpiration activity of a wax covering ; (c) the relation to transpiration 

 of leaf thickness, specially in the chlorophyll layers. On all of these points we are still 

 largely ignorant ; but everywhere in Nature we see form suiting itself to function to a 

 degree that often effects remarkable alteration in structure, and we may therefore suggest 

 hypothetically that the apparently anomalous details of the above hybrid may receive a 

 true interpretation on the line indicated. 



Starches of Hedychium Species and of their Hybrids. — In two cases already 

 described it has been stated that appreciable differences exist in the starch granules of 

 parents and hybrids, those of the latter being between those of the parents. But as 

 these were very small and variable in size, the discovery of forms in which size was com- 

 bined with tolerable uniformity was very welcome. Such were obtained from a series of 

 Hedychium hybrids, one of which has already been named. 



H. Gardnerianum, the one parent of H. Sadlerianum, forms strong rhizomes, whose 

 storing cells are large, but scantily filled with starch in all that I have examined. Each 

 starch grain is a small flat triangular plate, measuring 10 to 12 m from hilum to base 

 (Plate VII. fig. 13), and the lamination is not very distinct. H. coronarium, the other 

 parent, forms smaller and fewer rhizomes, and the starch-storing cells are from half to 

 three-fourths the size of the last, but these are densely filled, particularly in the central 

 parenchyma, with large starch granules. Each is ovate, or in some cases is tapered 

 rather finely to a point at the hilum. They are from 32 to 60 ^ long, measuring as 

 before, and the lamination is very marked (Plate VII. fig. 15). The cells of the hybrid 

 are on the average between those of the parents ; but if one may judge by opacity of cells, 

 the amount of stored starch approaches more closely to that of the latter parent. The 

 grains may best be described if we suppose a rather reduced one of the first parent to be 

 set on the reduced basal half of one of the latter. The lamination also is more pronounced 

 than in the first, less so than in the second (fig. 14). 



A second cross was effected by Mr Lindsay with H. coronarium, and examination of 

 the rhizome starches proves that the second hybrid approaches very closely to the 

 species parent. But the grains of H. Lindsayi illustrate microscopically a phenomenon 

 which has been repeatedly referred to, viz., the greater variability and instability of a 

 second over a first hybrid, for many of the grains (in some specimens the majority) 

 have fantastic shapes, appearing as if undergoing rapid disintegration by leucoplasts, or 

 perhaps more truly as if the latter were incapable of building up the shells of starch in 

 a regular and uniform manner. 



A set of crosses has been effected between H. elatum and H. coronarium. The 



