44 MINNESOTA BOTANICAL STUDIES. 



spiral threads to which the seeds adhere, and shows figures of 

 two-spiraled elaters without the membrane. In his specific 

 description of Targionia and AntJioceros he states that there 

 are many seeds, each fixed to an elastic twisted thread.^ 



The presence of starch-grains in elaters has been known for 

 some time. Von MohP speaks of the starch-grains in the 

 young elaters of Jungermannia muUifida and says that the 

 starch disappears as the spiral bands are formed and the elater 

 ripens, and again^'^ states that the starch in the elaters of 

 liverworts vanishes when the spiral fibre is developed in them. 

 Kienitz-GerlofE observes that he has never seen starch in the 

 elaters of Marchantia polymorpha,^^ but that those of Junger 

 mannia Mcuspidata^- are filled with starch-grains which later 

 on yield material for the double spiral band. 



Perhaps more attention has been devoted to the thickening 

 of the walls of the elater and the number and arrangement of 

 the bands than to any other particular. A great deal of this 

 information, however, is inaccurate. Hedwig illustrates seven 

 difiierent types of elaters with spiral thickenings, of which 

 those of Conocephalus alone are entirely correct.i^ He de- 

 scribesi* the elaters as varying much in the different species as 

 to composition and length, and as having two, three or four 

 interwoven filaments which seem to be contained in the very 

 thin membrane. Kny, in connection with an article on the 

 Hepaticae,^^ shows a figure of Aneura palmata drawn as if the 

 thickening band were external. The subject seems to have 

 been thoroughly studied by Kutzingi*^ -^i^o states that "the 

 elaters of Marchantia are composed in their early stages of a 

 gelatinous substance and contain a few chlorophyll grains 

 which are more or less scattered about. Soon one notices that 

 the chlorophyll grains become associated by means of very 

 fine and delicate colorless bands, which gradually develop into 

 the spiral bands lying on the inner wall of the cell. By further 

 development these spiral bands lose their chlorophyll grains 



8. Withering, loc. cit. 390. 



9. Von MoU, Einige Beraerk. u. d. Eutw. u. d.Baud. Sporen. d. crypt. Gew. F^ora 

 37 21Ja. 1833. 



10. VonMohl. Grundz. d. Anat. und. Phys. d. veg. Zelle in Eud. Wagner. Haudw. d. 

 Phys. 207. 1851. 



11. Kienitz-Gerloa; Vergl. Untersucb. u. d. Entw. d. Leber. Sporog. Bot. Zeit. 38: 171. 

 1874. 



12. Kienitz-Gerloff, loc. cit. 215. 



13. Hedwig, Tbeoria Gen. et. Fruct. Tab. XXVIII. 1798. 



14. Hedwig, loc. cit. 184. 



15. Kny, Beitr. z. Entw. d. laub. Leberm. Jahrb.f. iviss. Bot. PHngsh. 4: Taf. VII. 1865 



16. Kutzing, Grundz. d. Phil. Bot. 2: 54. PL 21, fig. 13 a. 1852. 



