1918] Kendall: Abscission of Flowers and Ft^uits in Solaiutceae 411 



Several interesting conclusions are brought out by an examination 

 of the above facts. In the first place, the abscission of the remains of 

 severed pedicels is probably independent of the transportation of 

 materials from the rest of the plant to the separation zone. It may 

 result from the action of the stimulus directly on the cells in the 

 vicinity of the separation layer and is, therefore, largely independent 

 of such phj'siological processes as transpiration which might conceiv- 

 ably enter in. In the second place, abscission induced by mechanical 

 injur}' is probably of the same nature as that of severed pedicels and 

 therefore probably results from the action of the stimulus directly on 

 the cells in immediate proximity to the separation layer. 



SUMMARY ' 



The final summary of results given below is presented under 

 several headings corresponding to those of the main body of the 

 paper. Unless otherwise stated, the results given may be taken as 

 applying to all the species of the Solanaceae in which abscission was 

 found to occur. First is presented a complete list of the species which 

 were investigated, indicating by 1 those in which floral abscission 

 never occurs, by 2 those in which it very seldom occurs, and by 3 

 those which were actually examined microscopically to determine the 

 histological structure of the separation zone and the method of 

 abscission. 



3 N. Tabacum var. maciophylla 



3 N. sylvestris 



3 N. Tabacum "Maryland" 



3 FiHlo4 (N. sylvestris X N. Tab. 



var. maerophylla) 

 3 F,H179 (N. sylvestris X N. Ta- 

 bacum "Cuba") 

 3 F,H36 (N. sylvestris X N. Tab. var. 

 angTistifolia) 

 N. glauca 

 3 N. rustica (2 varieties — not bra- 



silia) 

 2,3 N. Bigelovii (3 varieties) 

 2 N. quadrivalvis (2 varieties) 

 2 N. multivalvis 

 X. Sanderae 

 N. rustica var. brasilia 

 X. suaveolens 



3 Solanum umbelliferum 



S. tuberosum 



S. jasminioides 

 3 S. verbascifolium 



S. nigrum 

 2, 3 loehroma tuljerosa 

 3 Oestrum fasciculatum 



Lycopersicum esculentum var. vul- 

 gare 

 3 L. esculentum var. pyriforme 

 1, 3 Petunia hybrida 

 1, 3 Salpiglossis sinuata 

 3 Datura sanguineum 

 1 Salpiclirora rhomboidea 

 1 Lycium australis 



