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THE AMERICAN NATURALIST [Vol.XLVI 



that they were derived from the bright wclli I of course 

 have no proof, but in the light of my study of A. amphora 

 it seems probable. They were campanulate forms, dif- 

 fering from the slender saccate A. b right welli even more 

 than the campanulate A. amphora differs from the 

 smaller types of its species. Seen in dorsal view, when 

 freely swimming in a drop of water without cover glass, 

 they presented almost the form of an equilateral triangle 

 with one rounded corner ; this was the posterior end ; the 

 entire opposite side being taken up by the loose napping 

 corona. I regret that, in my haste, I was unable to study 

 these forms precisely, and much less to prove their re- 

 lationship. But I hope that the isolated observation may 

 perhaps induce others to seek among crowded stocks of 

 Asphntchna of different species for rare and much mod- 

 ified forms. If, as I believe will be the case, they are 

 found to occur occasionally in A. bright icelli and perhaps 

 other species, it will throw an added light upon the changes 

 which so readily take place in A. amphora. The rarity 

 of their occurrence will render clearer the relationship of 

 the phenomena to the recognized instances of mutation. 



Before closing the discussion of facts relative to the 

 specific determination, statements must be made with re- 

 gard to the males and to the resting eggs. Similar males 

 are produced by all three of the forms which the am- 

 phora-like Asphntchna assumes. The humped and cam- 

 panulate types produce them copiously ; the saccate type 

 but rarely and at periods when it is about to pass over 

 into the humped form. These males are always of the 

 well-known type bearing two lateral humps. They quite 

 agree with Rousselet's determination, except that he evi- 

 dently assumes the size to be uniform, whereas I find it to 

 be extremely variable, the limits being as three to one. 

 The largest males, often present in abundance, reach fully 

 the size of the humped females ; i. e., a length of 1500/*. 

 The cause for the wide divergence in size is the varying 

 degree of development at birth. This affects them as it 

 affects the young females, except that the young males, 



