196 



PRINCIPLES 



OF PLANT-TERATOLOGY. 



some, again, by the fact that the ovule is often 

 replaced by a vegetative bud. Others held that the 

 ovule is an organ sui generis, e. g. Schmitz, Sachs, 

 Strasburger, Goebel, Eichler, and Bayley Balfour. 

 The foliolar theory of the ovule was held by Brong- 

 niart (the founder), Robert Brown, Caspaiy, Cramer, 

 Prantl, Warming, Celakovsky, and Velenovsky. 



An account in brief outline will now be given of 

 some of the changes undergone by ovules as fully 

 described by Celakovsky in numerous papers. He 

 regards the ovule as, in a general way, the homologue 

 of a trilobed leaflet of the carpel, of which the 

 terminal lobe, inrolled towards the upper surface to 

 form a cup-shaped structure enclosing the nucellus 

 (this having the value of a sporangial emergence 

 borne on the upper surface of the lobe) is the equiva- 

 lent of the inner integument ; while the two lateral 

 lobes, fused by their inner margins across the upper 

 surface of the leaflet, represent the outer integument. 

 It is to be noted that, in accordance with the law 

 of laminar inversion, the lower surface of the outer 

 integument contacts the lower surface of the inner 

 integument. The above-outlined general position of 

 the author derives its entire support from the facts 

 revealed by the so-called " monstrosities " of ovules 

 where gradual transitional forms between the normal 

 ovule and the trilobed or simple leaflet have been 

 observed. 



In abnormal ovules of the garlic-mustard {Sisym- 

 brium Alliaria) it was the inner integument which 

 exhibited the greatest amount of proliferation or leafi- 

 ness ; and another remarkable feature consisted in the 

 preponderating tendency to proliferation of the funicle 

 rather than of the outer integument. So that the ovular 

 leaflet sometimes assumed the form of a leafy structure 

 (the funicle) bearing the inner integument, subtended 

 by the rudimentary sheath of the outer integument, on 

 its lower surface (PI. XL VIII, fig. 6) ; or, in some 

 cases, the outer integument may be completely absorbed 



