292 PHYSIOLOGICAL BOTANY. 



ovary. But may not the entire nucleus be an embryo ? 

 He includes amongst false arils the remarkable envelope 

 of the seed in Opuntia, the formation of which is here 

 shown to occur from two lateral expansions of the funiculus. 

 Moreover, the false aril of Euonymus latifolius, which has 

 been already mentioned, belongs here ; the tubercle in 

 the Euphorbiacese also is only the thickened margin of 

 the exostome, and the aril, as it is called, of the Polyga- 

 lacese agrees in many points with it. In Clusia flava we 

 must assume, that the outer envelope of the nucleus, 

 which is simple in the greater part of its extent, becomes 

 doubled, divided into two unequal prolongations beyond 

 the exostome. It is doubtful whether the Nutmeg does 

 not belong here. The author denominates by the term 

 Strophiola the glandular excrescences situated along the 

 raphe ; they are independent of the umbilical cord and 

 the exostome, and he mentions, as an example, the seeds 

 of Arum Canadense. Finally, the history of the nucleus 

 of some species of Veronica, especially V. liederapfolia and 

 V. Cymbaria, with remarks upon the genus Avicennia. 

 The peculiar operculum of the seed of the latter originates 

 from the embryo-sac, which in Veronica is converted into 

 albumen. The embryo- sac of Avicennia ruptures the 

 nucleus in the ovary, and the embryo also ruptures the 

 embryo-sac by too rapid germination in the fruit. In 

 Veronica hedercefolia, the nucleus at an early age is 

 reduced to the embryo-sac only, and has no covering. 

 The details must be obtained by the examination of the 

 author's work itself. 



In a memoir which M.Guglielmi Gasparrini read before 

 the Academy of Naples as early as ] 842, he endeavoured 

 to show, that the fruit of the Opuntia is merely a branch 

 adapted for this purpose. The nuclei are at first situated 

 in the central cavity in rows, the wall of the cavity is 

 not a distinct organ, like the ovary in other plants, but 

 consists of a special complicated fibrous tissue, which is 

 produced for this structure. This fibrous tissue is both 



