SEXUAL REPRODUCTION IN DIATOMS 95 



tnlii var. tciiiiistrhita Cicirlcr, Cy mat u pleura solea (Brcb.) W. Sm., 

 Ewiotia avciis I'.hr., E. pexuosa Kiir/., E. formica I^lir., E. pectrnalis 

 (Kiitz.) Rabli., Naviaila crytocepbala var. veneta (Kiitz.) Grun., 

 Rboicosphema nirvata (Kiitz.) Grun., Si/rirella caprovii Breb., S. 

 spleiidida Ehr., 5. striatnla Turp. 



(2) The gametes behave anisogaiiiously. Navicula seminiilimi 

 Grun. coccoiieis pediaihis Ehr., C placeutula Ehr., C. placeiitula var. 

 pseudolincata Geitler. 



Reduced Type B 



One mother cell develops an auxospore through automixis (Figs. 

 16 to 19). 



( 1 ) Two gametes of one mother cell copulate with each other. 

 Achuaiitbes siihsessilis Kiitz., Cyclotella meneghiiiiana Kiitz, Gom- 

 pbonevia coustvictuvi var. c a pit at a (Ehr.) V. H., Form I. 



(2) The sexual nuclei of a mother cell copulate. Ampbora nor- 

 iihwii Rabh., Bacillaria paradoxa Gmelin (?), Chaetoceras boreale 

 Baily, C deiisiivi CI., Gravmiatophora marina (Lyngb.) Kiitz., Libel- 

 lus cojistrictiis (Ehr.) DeT. (?), Navicula coustricta Grun. (?), 

 Nitzschia palea (Kiitz.) W. Sm. 



Reduced Type C 



The auxospore formation is apomictic (Figs, 20 to 22). 



( 1 ) From one mother cell there develop through vegetative di- 

 vision two auxospores. Acbuautbes loiigipes Ag. (?), Bacillaria para- 

 doxa Gmelin (?), Coccoiieis pedicidiis Ehr., Libelliis constrictus 

 (Ehr.) DeT., Navicula constricta Grun. (?), Rbabdoiiema arcuatuin 

 (Lyngb.) Kiitz., Syiiedra affinis Kiitz., Tabellaria sp. 



(2) From one mother cell (the mother cells may pair) there 

 develops one auxospore. 



(a) Parthenogenetically. Bacillaria paradoxa Gmelin (?), Coc- 

 coiieis pedicuhis Ehr., C. placeutula Ehr., C. placentula var. klino- 

 rapbis Geitler, C. placeutula var. lifieata (Ehr.) CI., C, placentida var. 

 euglypta (Ehr.) CI., Cymatopleura elliptica (Breb.) W. Sm., C. solea 

 (Breb.) W. Sm., Cymbella cistula (Hemphr.) Kirchn. (?), C. swna- 

 treiisis Hust. (?), C. ventricosa Ag. var. I, Grainmatopbora mariiia 

 (Lyngb.) Kiitz. (?), Meridion circidare (Grev.) Ag., Navicida 



