328 Mr. Griffith on the Root-Parasites referred to Rhizantheae, 



necessary relation with the cavity of the ovarium, or in the great generality of 

 cases with the placentae. 



Although that definition which regards its secretory nature is the most cor- 

 rect, it is not sufficiently so ; that which regards it as terminating the style 

 is often contradicted ; and even setting aside such exceptions as must arise 

 from the not unfrequent absence of a style, it would not by any means be 

 always correct when that part of the pistillurn does exist. 



M. Schleiden* has made an improvement in defining this organ, and, taken 

 with the context, his definition appears to me to be tolerably complete both 

 as regards situation and function. Nevertheless, in the actual definition the 

 stigma is still referred to the style. 



In my opinion the stigma is better defined as the external communication 

 of the conducting tissue, which itself communicates with the placentae, and is, 

 in several cases at least, (as in Trewia nudiflora,) manifestly a continuation 

 from them. To this Dr. Lindley would appear to have approached in some 

 remarks on Fabiana imbricataf, but he has considered it a special, not a 

 general structure. If the expression I have made use of above as describing 

 in general terms the stigma be correct, its situation may be totally inde- 

 pendent of the style, even when it exists, or what may be considered as such. 

 This I believe will be found to be the case. 



Of the theoretieal origin of the stigma* I would speak with caution. In 



* "On the Development of the Organization in Phamogamous Plants," Lond. and Edinb. Phil. 

 Mag. vol. xii. p. 182. 



t Bot. Register, vol. xxv. t. 59. Dr. Lindley is correct in stating the indusium to belong to the 

 style, as I have ascertained from studying its development in Sccevola Taccada. 



X In a memoir on Cyrtandracea> by Mr. Robert Brown', with which I became acquainted several 

 months after this was written, the following opinions regarding the stigma are given :— 



" Each simple pistillurn or carpel has necessarily two stigmata, which are to be regarded not as ter- 

 minal, but lateral." 



» In the compound but unilocular ovarium, while the placenta of the adjoining carpels are united, 

 the st.gmata of each carpel are generally confluent. But this rule admits of exceptions, as in Par- 

 nassta, m many Crucifer* and in Papaverace* ; in all these cases the stigmata as well as the placenta, 

 of the adjoining carpels are confluent." 



» Characters dependent on the various modifications of stigmata are of less value, both in a systematic 



1 PI. Javan. Rarior. part 11. p. 106, under Loxonia acuminata. 



