556 PROCEEDINGS OP THE ACADEMY OP [1895. 



Instead of having exhausted the study of the subject by this time, it 

 seems to be gaining in interest. 



Naturally enough, it was not the tendency of scientists to try to 

 disprove what was evidently true from the observations of Sprengel, 

 but rather to develop more fully our knowledge of cross-fertilization. 

 I need only refer to the famous work of Darwin, to that of the 

 well-known German botanists, Hildebrand, H. Muller, Kerner, and 

 to that of the many close observers of our own day. 



The fact that cross-fertilization is of utmost value to the individual 

 species has been emphasized by Darwin. In fact, this great dis- 

 coverer contends repeatedly that pollen applied to the pistil of 

 the same flower is a positive injury to the species. It is curious 

 to note how this idea has influenced the authors of botanical 

 text-books. As one instance in many, I need only refer to Gray's 

 Structural Botany. To the rather long chapter devoted to the 

 description of the adaptation of flowers to insure intercrossing, a few 

 paragraphs are added in which the writer, it seems to me rather 

 unwillingly, admits that there are also special adaptations to insure 

 close fertilization, in fact, that there are cases which positively ex- 

 clude all chances of a cross. Of cleistogamous flowers, Gray says : 

 "Here the intention and the accomplishment of self-fertilization are 

 unmistakable. This peculiar dimorphism consists in the production 

 of very small or inconspicuous and closed flowers, necessarily self- 

 fertilized and fully fertile in addition to ordinary, conspicuous, and 

 much less fertile, though perfect flowers.'" He then continues: "It 

 has been said that the ordinary flowers in such plants are sterile, 

 and perhaps they always are so, except when cross-fertilized: in most 

 cases they are habitually infertile or sparingly fertile. Probably 

 they suffice to secure in every few generations such benefit as a cross 

 may give, while the principal increase is by cleistogamous, self- 

 fertilization, which thus offsets the incidental disadvantage of the 

 former mode." I have quoted the writer verbatim, because the 

 extract shows so plainly his mental attitude in regard to the signifi- 

 cance of this phenomenon. Here we have a concession in regard to 

 the extreme fertility of cleistogamous flowers, followed by a sug- 

 gestion in regard to the few mostly infertile conspicuous flowers 

 which accompany the former and from these, and the statement that. 



1 Gray's Structural Botany, p. 241. 



