SEX IN PRO 1 (T/OA 1 39 



interpreted the evidence as indicating- autogamy followed by a two- 

 division nieiosis and completed by four-part cytoplasmic divisions. 

 Although suggestive, the evidence lacks completeness and alternative 

 interpretations can be made. None of the accounts of syngamy in 

 the euglcnoids is complete and satisfactory. 



Order Cbloromonadina 

 No instances of syngamy in this group have been found. 



Order Dinofiagellata 



There is some evidence for syngamy in the dinoflagellates, drawn 

 mostly from studies on Noctihica (Fig. C, 1-5), certain free-living 

 peridinians, and a few^ parasitic species. 



Cienkow'ski (1871a) described fusion of adult specimens of 

 Noctihica, but the evidence can readily be interpreted otherwise, 

 as can also that presented by Ishikawa (1891). Both cases appear 

 to be examples of fusion following incomplete binary fission. On the 

 other hand, evidence that minute sw^armers (3 to 5) may undergo 

 syngamic fusion is somewhat more convincing. Pratje (1921) saw 

 swarmers adhering in pairs and complete fusion of isolated pairs, but 

 did not see nuclear fusion. Hofker (1930) observed that swarmers 

 derived from a single individual did not fuse. When he isolated to- 

 gether a number of individuals undergoing swarmer formation (Fig. 

 C, 3), he found many active young specimens of Noctihica the next 

 morning and these developed into typical adults. He believed that the 

 young specimens had resulted from fusion of swarmers. Gross (1934) 

 also found that swarmers from a single parent did not unite, but 

 those from different parents did, accompanied by nuclear fusion. 

 However, he did not follow the development of the "zygotes" thus 

 formed. Thus wc have a highly suggestive series of observations in- 

 dicating syngamy of sw^armers in Noctihica, w^hich, however, lack 

 completion. 



Apparently Joseph (1879) was the first to report cell fusion in 

 the Peridiniidae, having seen united pairs of Feridiniinn stygiwii. 

 Stein ( 1883 ) showed a number of illustrations which were interpreted 

 as indicating stages of "conjugation" for Gle7wdimwn piitrisciihis 

 (Stein), Heterocapsa triqueta Stein, and Amphidiminii laciistre Stein, 



