THE STRUCTURE OF THE UNDULATING MEMBRANE 

 IN THE CILIATE BLEPIIARISMA. 



ROBERT CHAMBERS AND J. A. DAWSON, 

 MARINE BIOLOGICAL LABORATORY, WOODS HOLE, MASS. 



It has for long been generally accepted ' that the undulating 

 membrane of ciliates is composed of a serried row of fine cilia fused 

 into a homogeneous-appearing membrane. This conception has 

 been based largely on the fact that the membrane, when treated 

 with fixatives, resolves itself into a linear series of very fine 

 fibrillae. Moreover, several investigators have remarked on the 

 occasional appearance of delicate striations in the living mem- 

 brane of certain ciliates. In addition to this Maier reports 

 having noticed, in the living specimen an actual breaking down of 

 the membrane into fibrillae for some distance inward from its free 

 border. 



It was thought of interest to study the behavior of the undu- 

 lating membrane in Blepharisma undulans by subjecting it to 

 manipulaton with the microdissection needle. 



A single blepharisma, in a shallow hanging drop in a Barber's 

 moist chamber, was held stationary by means of a microneedle 



thrust into the posterior end of the body, Fig. i, a. Another 

 needle, Fig. i, b, having a very slender and long tapering tip (the 



1 For a review of the literature on this subject see H. N. Maier, " 1 >n tVinere Bau 

 der Wimperapparate der Infusorien," Arch. f. Protistenk., 2, 73 (1903). 



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