OMPHALIA FLAVIDA 



419 



positive geotropic stimulus, but some turned upwards, some down- 

 wards, and some sideways. Also, when rotated slowly on the 





Fig. 212. — Omphalia flavida. Stages in the development of a gemmifer on a leaf of 

 Bryophyllum cnlychmm. A, a very young stage in median-vertical section 

 showing the primordia of the pedicel and the gemma. B, the pedicel, which 

 is still straight, has elongated by intercalary growth at its upper end, and the 

 gemma has become swollen. C : the pedicel has become bent (repulsion 

 curvature) and is still elongating by intercalary growth under the gemma ; 

 the gemma has developed a circular cavity between the pedicel and the apophy- 

 sis ; hairs have grown out from the pedicel and infection hyphae from the 

 periphery of the gemma. D, the circular cavity has enlarged and the pedicel is 

 still growing in lengtli. E : the pedicel is now full-grown ; its end has become 

 sigmoidally bent (geotropi(^. curvatures) and has broken away from the gemma 

 which now has its axis horizontal ; the gemma is holding on to the end of the 

 pedicel by its apophysis only. F, the gemma is being blown away from its 

 pedicel by the wind and is travelling in the direction shown by the arrow. 

 G, the underside of a ripe gemma after leaving the pedicel ; the central opening 

 came into existence when the gemma slipped of? the stipe. H, a gemma which 

 has settled on a leaf and is infecting it by means of its infection hyphae which 

 have grown in length. Drawn by A. H. R. BuUer and Ruth Macrae. Mag- 

 nification, 47. 



klinostat during their development, the pedicels all became more or 

 less curved, the direction of the curvature being usually away from 

 the centre of the plate toward the edge of the radiately growing 



