Jan. 1S92.] THE BOTANICAL SOCIETY OF EDINBURGH. 243 



produces a corresponding excavation in tlie sepal covering 

 it. Once formed, the pouch is found of advantage as a 

 honey-receptacle, and is retained for that purpose. 



4. Dehiscence. — In many Crucifera? the anthers of the 

 longer stamens do not dehisce directly inwards, but are 

 severally twisted through 45° each towards the nearest 

 short stamen, so that the entrance to the more important 

 nectary within the base of the latter is surrounded by three 

 dehiscing anthers. This is well seen in Nasturtium officinale, 

 Alliaria, Brassica Sinapis, Lqiidiuvi Smithii, and Cravibe 

 maritima. In the last- mentioned species, Cramhe maritima, 

 the filaments of the longer stamens are broadened and 

 flattened out with a groove along the middle line ; the 

 filament ends at the top in two horns, of which one bears the 

 anther, while the other is pressed against the ovary. The 

 groove above mentioned guides an insect's proboscis to the 

 honey. No other Crucifer except Teesdalia nudicaulis, 

 which is quite abnormal (see Mtiller, loc. cit.), has so compli- 

 cated an arrangement as has this species.* 



5. The Longer and Shorter Stamens dehisce at 

 Different Periods in some Crucifer.e. — This is the case 

 in Cardamine p^^atensis, C. ficxuosa, Alliaria, and Brassica, 

 monensis, where the long stamens shed their pollen some 

 time before the short stamens are ripe. 



6. Eelative Position of Anthers and Stigma. — In all 

 the forms known to me, except Cardamine amara and 

 Siibularia aquatica, the stigma when mature is above the 

 level of the anthers of the short stamens ; these latter are 

 therefore unable to effect self-fertilisation. On the other 

 hand, pollen from the anthers of the long stamens may 

 produce self-fertilisation in most Cruciferse though it is only 

 in Arahis hirsuta and A. Tlicdiana that it seemed to me 

 inevitable. 



The Embryo-sac in Myosurus minimus, Linn. By 

 GusTAV Mann. 



* Kunth iu Bot. Ceiitralblatt, 1891. 



