96 Macfarlane — Observations on Some Hybrids 



of parental hair inherited in greatly reduced numbers and of 

 much smaller size, and another type inherited in reduced 

 numbers, but of exactly the same size. Still further, the 

 hybrid inherits bilobed glands from D. intermedia in moderate 

 quantity. Three types of epidermal glandular appendage are 

 thus inherited by the hybrid from its parents. 



I do not propose to describe in detail at present all the 

 points of floral or fruit and seed structure. The careful 

 observations of another season will be needed before exact 

 comparisons can be made. It may be said, however, that the 

 pollen grains of D. filiformis are richly granular, largest in 

 size and measure 56 11 across. Those of D. intermedia are 

 also granular and plump ; they measure 44 [x across. Most 

 of the hybrid grains are more or less starved or poor in proto 

 plasmic substance. They measure 48-50 {J., so that develop- 

 ment of the pollen grain w^alls has proceeded perfectly, though 

 the enclosed fertilizing substance appears to be imperfect. 

 The ovules and seeds of both parents matured well, those of 

 the hybrid remained small and in most instances developed as 

 empty or nearly empty shells. Cultivation and future study 

 will demonstrate how far this may be a constant character. 



The naked eye and histological details described above em- 

 phasize the position first fully established by the writer,* that 

 a hybrid is, as a rule, down to its minutest details, a blended 

 reproduction of both parents in which the morphological and 

 physiological details of each are reduced by half In no case 

 has it been possible to detect the entire loss in the hybrid of 

 some parental condition, and this cannot be too strongly 

 insisted on in view of the loose theoretical reasonings often 

 indulged in now on questions of heredity. Peculiarities of 

 structure, and equally, it seems, of function, are not readily 

 lost, but may persist, in a gradually reduced state, in several 

 succeeding generations. 



A glance at the comparative results, however, equally 



* Trans. Roy. Soc. Edin. Vol. XXXVII, p. 203. 



