ADDITIONS. 



Note, Page 4. — The word Cycads has inadvertently been 

 substituted for Zwrniads. The statement is wrong if Gycad is 

 compared with Stangeria. 



Page 89. — Pringsheim has lately published some additional 

 observations on the impregnation of CEdogonium, in Monats- 

 bericht der Kon. Ak. der Wissenschaften zu Berlin, 1856. 

 The upper cell of the antheridium produces two elhptic bodies 

 which pass into the cavity of the spore -cell and there effect the 

 impregnation of the spore. The antheridia are first formed 

 within special cells, from which they escape and move about 

 by means of a coronet of cilia, till they fix themselves upon 

 the spore-cells. Dippel has called in question some of Prings- 

 heim's observations in Flora, 1856, No. 31, 32, without, how- 

 ever, at all shaking them. Pringsheim proposes the name of 

 Androspores for these bodies, to distinguish them from other 

 Microgonidia. See also Cohn on Sphceroplea awnulina, 

 translated in Ann. d. Sc. Nat., Sept. 1856. 



Page 157. — An elaborate paper on Chytridium has lately 

 been published by Braun in the Transactions of the Berlin 

 Academy, 1856. Some of the species closely resemble the 

 antheridia of CEdogonium and Bulbochcete, and as they occur 

 on the fertile cells they require to be carefully distinguished. 



Page 168. — Thuret has published some additional facts on 

 the antheridia of Algae, in Ann. d. So. Nat., Jan. 1855. He 

 has found these organs in seventy Ehodosperms.* In Ecto- 



* These belong to the genera Porphyra, Bangia, Callithamnion, 

 Griffithsia, Hcdurus, Ceramium, FurceUaria, Oigartina, Phyllophora, 

 Lomentaria, Rhodhymenia, Plocamium, Helminthocladia, Helminthora, 



