170 MISSOURI BOTANICAL GARDEN. 



The method of the shedding of the pollen in the Anffio- 

 sperms is a subject very briefly treated inthe general works 

 on morphology and physiology. Goebel in his Organoo;- 



raphie calls attention to the obscure nature of many 

 points in this phenomenon, and Coulter and Chamberlain 

 in their recent work on the morphology of Angiosperms 

 spetik of the need of a thorough investigation of the sub- 

 ject, especially from the developmental point of view. 

 Most general works treat this point with the same or greater 

 brevity and need not be mentioned separately. 



Histologically, anthers have been investigated and their 

 minute anatomy interpreted more or less satisfactorily by 

 several writers, among whom may be mentioned Mohl, 

 Purkinje, Schrodt, Leclerc du Sablon, Chatin, and Stein- 



brinck. 



So far as I am aware, no special treatment of the api- 

 cally dehiscent anther has been attempted from a morpho- 

 logical, histological or ecological point of view. 



PURPOSE OF INVESTIGATION AND SCOPE OF PRESENT PAPER. 



My purpose in undertaking the present investigation 

 was threefold: 1. The compilation of a systematically 



g 



i 



cence by pores, for use in future biological work. 2. The 

 demonstration of any similarity of structure in apically 

 dehiscent forms of different systematic affinities or the ex- 

 i.stence of possible correlative modifications in the parts of 

 the flowers sho ving this method of dehiscence, if such exist. 

 3. The establishment or the refutation of the hypothesis 

 that the flora of certain of the main divisions of the earth's 

 surface is richer in apically dehiscent forms than that of 

 others. 



These three purposes were quite satisfactorily accom- 

 plished in the spring of 1903. During the time which has 

 elapsed since "the writing of my first manuscript I have 

 added practically no new genera or species to my list. I 



