one, Trichomastix ( B ), possesses four flagella, and the other two, Trichomonas, apparently three only: the two latter possess the frill, which is lacking in the first. But it is impossible to doubt that when the frill is present (as in A and C ), its outer edge is constituted by the apparently missing flagellum ( a ), which has become attached to the body of the creature at the point c , near its posterior end; and all along its course, the superficial protoplasm has been drawn out into a film, between the flagellum ( a ) and the adjacent surface or edge of the body ( b ).
Moreover, this mode of formation has been acôÙtualôÙly witôÙnessed and deôÙscribed, though in a someôÙwhat exôÙcepôÙtional case. The little flaôÙgelôÙlate monad HerôÙpeôÙtoôÙmoôÙnas is norôÙmalôÙly desôÙtiôÙtute of an unôÙduôÙlaôÙting membrane, but possesses a single long terminal flagellum. According to Dr D. L. Mackinnon, the cytoôÙplasm in a certain stage of growth becomes somewhat ãsticky,ã a phrase which we may in all probability interpret to mean that its surface tension is being reduced. For this stickiness is shewn in two ways. In the first place, the long body, in the course of its various bending movements, is apt to adhere head to tail (so to speak), giving a rounded or sometimes annular form to the organism, such as has also been described in certain species or stages of Trypanosomes. But again, the long flagellum, if it get bent backwards upon the body, tends to adhere to