l98 PEiNCIPLES OF PLANT-TEEATOtOGt. 



leaflet cannot be tlie outer integument, because forma- 

 tion of the .inner integument being always the primary 

 process (ovular development being basipetal), this 

 organ could not arise as an emergence from the outer 

 integument ; it must also be situated invariably on 

 its lower surface. The leaflet in question must there- 

 fore contain within itself both inner and outer integu- 

 ments. This particular type resulted from the 

 proliferating tendency setting in at the period when 

 the ovule was nothing but an undifferentiated rudi- 

 ment, containing within itself the two integuments in 

 pote)itid. The integuments, whether the outer or the 

 inner, once laid down as completely sheathing struc- 

 tures, never proliferate as laminge. Hesperis is 

 particularly interesting as having exhibited a case of 

 a proliferated outer integument bearing two or more 

 inner integuments, the extra ones occurring on the 

 lateral lobes of the leaflet (PI. XL VIII, figs. 13 and 1 4) ; 

 this case, as Celakovsky has elsewhere pointed out, is of 

 considerable value for the interpretation of the female 

 parts of Gupressns., 



Celakovsky also describes virescent ovules of Aqui- 

 legia, and these are not easy to understand. The fii-st 

 stage, in which proliferation sets in rather late, shows 

 the inner integument seated on the upper surface of the 

 " basal lamina," the two lobes of which are bent back 

 and fused together behind, instead of, as in all other 

 cases, in front of the inner integument. As this lamina 

 is to constitute the outer integument, there here occurs 

 an apparent contradiction to the usual law of laminar 

 inversion ; but our author finds it to be only apparent, 

 for differentiation into an upper and a lower surface 

 has not yet taken place in the inner integument. In 

 the second stage there is an anatropous cup-shaped 

 structure which, from the mode of development and 

 the various modifications occurring during the meta- 

 morphoses, is shown to be the inner integument, with 

 which the outer integument is intimately fused along 

 its whole length; the whole constituting a single un- 



