130 



BRITISH FLOWERING PLANTS 



the house and placed them on my billiard-table. They 

 were thrown from one end completely beyond the other, 

 in some cases more than twenty feet. The mechanism by 

 which this is effected has been described by Leclerc du 

 Sablon.^ He suggests that the fibres forming the rods 

 are thicker and therefore contract more on the outer side, 

 thus throwing the rods into a state of tension, so that 

 eventually they burst away. 



In some Geraniums the seeds are reticulate, and in 

 others they are smooth. This seems to me to be con- 

 nected, with their relation to the carpel. This is shown 

 in the following table : — 



0. sylvaticum 



pratense 



rotundifolium 



columbinum 



0. JRobertianum 

 „ lucidum 

 „ phceum 

 „ molle 

 „ pusillutn 



In Erodium 



Carpels not detached, hairy, not reticulate. 

 Seeds thrown and reticulate. 



Carpels thrown, reticulate. Seeds smooth. 



also, the seeds remain in the carpel, and 

 are practically smooth, the 

 reticulations, if present, 

 being very small. 



In the seedlings the 



Fig. 76. — Section through em- 

 bryo of Geranium, show- 

 ing the mode of folding 

 of the cotyledons. 



two "halves" of each coty- 

 ledon are unequal. This 

 is due to the manner in 

 which the cotyledons are 

 folded. In the Cabbage and Mustard we have seen that 



1 Ann. Sci. Nat. ser. 6, xviii. (1884). 



Fig. 75. — Seedling of Geranium 

 sanguineum. Nat. size. 



