POLLINIFEKOUS OVULES. 187 



of the ovule, while the pollen was formed within the 

 nucleus. In no case was any trace of embryo sac 

 to be seen. 



The main interest, as Mr. Salter remarks, in these 

 cases is physiological ; so far as structure alone is con- 

 cerned, there does not appear any reason why pollen- 

 grains should not be developed in any portion of the 

 plant ; the mother cells in which the pollen is formed 

 not differing, to all outward appearance, from any other 

 cells, imless it be in size. 



The fundamental unity of construction in all the 

 organs of plants could hardly be better illustrated than 

 by these cases; while, in spite of their exceptional 

 nature, they must be of great interest physiologically, 

 as showing the wide limits of possible variation which 

 thus may even involve the sex, " for an ovule to 

 develop pollen within its interior," says Mr. Salter, 

 " is equivalent to an ovum in an animal being converted 

 into a capsule of spermatozoa. It is a conversion of 

 germ into sperm, the most complete violation of indi- 

 viduality and unity of sex. * * * * The occurrence 

 of an antheroid ovule and a normal ovule on the same 

 carpellary leaf reahses the simplest and the most abso- 

 lute form of hermaphroditism." 



It must, however, be remarked that the term sub- 

 stitution would be preferable to conversion. There is, 

 at present, no evidence to show that the germinal 

 vesicles were present in these cases ; on the other 

 hand, it seems most probable that they were not, so 

 that the presence of the pollen -cells must be con- 

 sidered as simply adventitious. It can hardly be 

 that they were, in the first instance, germinal vesicles, 

 which, in course of time, became so modified as to 

 assume the appearance of pollen-grains. Between the 

 nucleus of the ovule and the tubercle of cellular 

 tissue constituting the primordial anther, there is Httle 

 or no difference, so that it may be said that, for a time, 

 there is no distinction of sex in the nascent flower, but 

 as development goes on, the difference becomes per- 



