466 ABORTION. 



of a vine as becoming dry, and even dehiscing by valves 

 like a capsule. 



In maize it occasionally happens that one or two of 

 the longitudinal series of fruits become abortive, leav- 

 ing a smooth furrow, at first of a greenish colour, but 

 ultimately of a reddish yellow. Often a second row of 

 fruits, opposite to the first, is also atrophied, so that 

 the whole spike changes its cylindrical form for a flat- 

 tened one.^ See also under Heterogamy, Meiophylly, 

 &c. 



Abortion of the ovules. In the case of a pluri-ovulate 

 ovary it rarely happens that all the ovules attain to 

 maturity, some never get fertilised, others, pressed on 

 by their neighbours on either side, become impeded in 

 their development, and finally disappear, or remain as 

 rudiments.^ This is the case, under ordinary circum- 

 stances, and still more so in the case of hybrid plants, 

 or of monsters. Where the outer coats of the ovule 

 become more or less leafy in appearance (see p. 262), 

 the inner investments become more or less atrophied, 

 or are even more frequently entirely suppressed, as is 

 also the nucleus. 



In other cases, a simple arrest of development takes 

 place ; the ovule, for instance, which should be ana- 

 tropal, remains straight, while the integuments, checked 

 in their development, form imperfect sheaths from 

 which the shrivelled nucleus protrudes. 



Depauperated Ferns. The preceding illustrations have 

 been taken from flowering plants chiefly, but a similar 

 defective development is manifested in cryptogamous 

 plants. The contraction and imperfect development 

 of the fronds of some varieties of ferns, hence called 

 depauperated, may receive passing notice, as also the 

 cases in which the sori or clusters of spore cases are 

 denuded of their usual covering, owing to the abortion 



> Moauin-Tandon, El. Ter. Veg.,' p. 325. 



* Alph. De CandoUe states that the position of the abortive ovules 

 affords a good chai*acter for discriminating between certain species of 

 Quercus. ' Bibl. Univ. Genev.,' 1862, t. xv, p. 929. 



