SIMM R I PRODUCTION IN DIATOMS 93 



InporhccM, li()\\c\ cr, is noniuil in that it possesses girdle bands. Thus 

 (he first vegetative cell is not symmetrical in appearance, and there- 

 fore it differs from subsequent vegetative cells. 



SUiMiMARY OF TVPIS OF AUXOSPORE FORMATION 



\ arious authors ha\e made classifications of the different types 

 of auxospore formations. The classification given below is taken from 

 Geitler (1932) but modified to include the results of more recent 

 research. 



Normal Type A 



Two mother cells each produce two gametes, which copulate 

 in pairs to produce two auxospores (Figs. 1 to 4). 



(1) The gametes are isogamous; the apical axes of the auxospores 

 are perpendicular to the apical axes of the mother cells. Amphi- 

 prora alata Kiitz. (?), Amphora coffaejonnis Ag., A. cymbelloides 

 Grun., A. ovalis Kiitz., A. ovalis var. pediciihis Kiitz., A. piisio CI., 

 A. veneta Kiitz., Auricula hyalina Karst., Denticula vanheurckii 

 Brun., Epithemia argus Kiitz. (?), E. sorex Kiitz., E. mrgida (Ehr.) 

 Kiitz., E. zebra (Ehr.) Kiitz., E. zebra var. saxonica (Kiitz.) Grun., 

 Navicnla radiosa Kiitz., Rhopalodia gibba (Ehr.) O. Miill., R. gibba 

 var. ventricosa (Ehr.) Grun. 



(2) Each mother cell produces a wandering and a resting gam- 

 ete. The apical axes of the auxospores are parallel to those of the 

 mother cells. Achnanthes lanceolata Breb., A. vmiutissima Kiitz., 

 Amphipleiira pelhicida Kiitz., A. rutilans (Trent.) CI. (?), Amphi- 

 prora alata Kiitz. (?), Anomoeoneis sculpta (Ehr.) Pfitz., A. serians 

 (Breb.) CI., Brebissonia boeckii (Ehr.) Grun., Cymbella affinis Kiitz., 

 C. caespitosa var. pediculiis (Ehr.) Brun. (?), C. cistula (Hemp.) 

 Grun., C. cymbijormis (Kiitz.) Breb. (?), C. gastroides Kiitz., C. 

 helvetica Kiitz., C. lacustris (Ag.) CI., C. lanceolata (Ehr.) V. H., 

 C. parva (W. Sm.) CI. (?), C. prostrata (Berk.) CI., C. simiatrensis 

 Hust., C. ventricosa Ag., C. ventricosa Ag. var. I and II, Frustidia 

 rhcmtboides var. saxonica (Rabh.) DeT., Goinphoiiema constrictum 

 Ehr., G. constrictum var. capitata (Ehr.) CI., G. geminatum (Lyngb.) 

 Ag., G. intricatiim Kiitz. (?), G. intricatinn var. dichotovnim (Kiitz.) 

 Grun. (?), G. longiceps Ehr. (?), G. olivaceinn (Lyngb.) Kiitz., G. 



