FREE-LIVING NEMATODES 5 



The spermatogenesis of Terschellingia polaris, n. sp. presents some 

 very interesting features which are noted in connection with the de- 

 scription. Kecently it has been suggested that of the two kinds of 

 spermatozoa Boveri and Schleip have shown to exist in the males of 

 the free-living generation of Khabdias bufonis, 2 one kind, supposedly 

 that producing males, becomes functionless, thus accounting for the 

 succeeding generation consisting solely of "parthenogenetic females," 

 found in frogs' lungs. The spermatozoa of Ascaris equorum 3 and (?) 

 Cystidicola farionis f have been shown also to be of two sorts. In all 

 these cases the two kinds of spermatozoa are very similar to each other, 

 so much so that the differences were long overlooked by keen observers. 

 In Terschellingia polaris the differences in the male generative cells are 

 of an extremely striking character, and seem to lend countenance to 

 the earlier suggestion of the writer, that spermatocytes may in their 

 reduction division produce polar bodies or their true homologues, abor- 

 tive spermatozoa. We realize now that there has been too large a 

 degree of assumption in taking it for granted that all four of the sper- 

 matozoa quartette are equivalent simply because they are similar in 

 form and size. A careful examination of their structure is revealing 

 important differences. 



Very possibly it is a comparatively minor phenomenon that the polar 

 bodies of eggs remain attached to their larger functional companion 

 cell. Taking this view, three of the four companion-spermatozoa may, 

 without violence, be regarded as homologues of the "polar bodies." 

 Whether they are functional or not is a matter that may be considered 

 quite apart from their history or structure. Generally speaking we 

 know little or nothing about their relative "potency." That all, or any 

 definite fraction of them are functional is more or less pure supposition. 

 What we know is that some of them are functional perhaps all, per- 

 haps not. 



Though these things are thus far outside our field of experience, they 

 constitute problems that seem certain soon to be attacked from the 

 experimental side, by following the history of specific members of the 

 spermatid quartette; and one object of this note is to call attention to 

 the fact that the free-living nematodes offer an attractive field for such 

 work. 



2 Rhabdias bufonis (Schrank 1788) S. and H. 1905 = " Rhabditis nigrovenosa." 



3 A scan's equorum Goeze 1782 = "A scan's megalocephala." 



4 (?) Cystidicola farionis Fischer 1798 = " A ncry acanthus cystidicola." 



