362 DISK. [BOOK J. 



iheAnnales des Sciences, n. s., III. 148. And, 3., to Fritzsche, 

 Ueber der Pollen: 4to., St. Petersburgh, 1837, with thirteen 

 coloured plates. In this last excellent work all the refine- 

 ments of optical instruments and chemical manipulation have 

 been employed in the investigation of the subject. 



10. Of the Disk. 



By this term are meant certain bodies or projections, 

 situated between the base of the stamens and the base of the 

 ovary, but forming part with neither; they are referred by 

 the school of Linnaeus, along with other things, to nectarium : 

 Link calls them sarcoma and perigynium ; and Turpin, phyco- 

 stemones. Their most common form is that of a fleshy ring, 

 either entire or variously lobed, surrounding the base of the 

 ovary (Plate V. fig. 4. e, 8. d.) as in Lamium Cobsea, Gratiola, 

 Orobanche, &c. ; in Gesnerads and Proteads the disk consists 

 of fleshy bodies of a conical figure, which are usually called 

 glandules hypogynce. It occasionally assumes the appearance 

 of a cup, named by De Candolle, in Pseonies and Aconites, 

 lepisma, a bad term, for which it is better to say discus 

 cyathiformis. In flowers with an inferior ovary (Plate V. 

 fig. 9. c, 7. c.) the disk necessarily ceases to be hypogynous, 

 and generally also to appear in the form of scales. In Com- 

 posites it is a fleshy solid body, interposed between the top 

 of the ovary and the base of the style ; and has given rise, 

 when much enlarged, to the unfounded belief in the existence 

 of a superior ovary in that order, as in Tarchonanthus. In 

 Umbellifers (Apiaceae) it is dilated, and covers the whole 

 summit of the ovary, adhering firmly to the base of the 

 styles; by Hoffmann it is then called stylopodium, a word 

 which is seldom used. 



It is the general opinion that a disk is really only a rudi- 

 mentary state of the stamens ; and it is thought that proofs 

 of the correctness of this hypothesis are to be found in the 

 frequent separation of the cyathiform disk into bodies alter- 

 nating with the true stamens, as in Gesnera; in its resemblance 

 in Parnassia to bundles of polyadelphous stamens ; and par- 

 ticularly in the fact noticed by Brown, that an anther is 



