1920] Johnson: Life Cycle of Echinostoma Bevolutum (Froclich) 349 



the divisions of the bladder containing the concretions I will term the 

 eoncretional descending tubes of the bladder (Id) ; the parts of the 

 bladder attached to the eoncretional descending tubes (Id) and ex- 

 tending backward to the posterior end of the body where each is joined 

 by three collecting tubules, will be called the ascending tubes of the 

 bladder (le) ; the collecting tubules are numbered 2a, 2b, 2c, and 2d, 

 respectively, starting from the most anterior one; the accessory col- 

 lecting tubules are designated as 3a, 3b, 3c, 3d, 3e, 3f, 3g, and 3h 

 respectively, also starting from the anterior end; the flame cells are 

 numbered individually from one to twenty-four, while their capil- 

 laries correspond, only with the "x" attached. The numbers of the 

 flame cells appear on the left-hand side, while the other designations 

 are on the right side. However, since the two sides are alike it will 

 be easy to transpose to the opposite side when necessary. 



The muscular sac of the bladder (lb) is located at the extreme 

 posterior end of the body. It may contract quite frequently to force 

 out waste. It is usually of medium size and from its posterior end 

 is given off a branch (la), running into the tail which quickly sub- 

 divides into two parts. The subdivisions run nearly at right angles 

 to the main branch, opening to the outside. Through the excretory 

 pores all the body waste seems to pass. As stated, the muscular sac of 

 the bladder usually appears in two parts connected by a narrow neck, 

 but this is far from being constant, so these parts will be spoken of 

 as forming a single part of the bladder (lb). 



The muscular descending tubes of the bladder (1c) join the mus- 

 cular sac of this organ (lb). These tubes of the bladder are also 

 muscular. I have seen them contract and expand to about twice their 

 average size nearly up to the ventral sucker. In the region of the 

 acetabulum the coiling of the muscular tubes of the bladder (lc) 

 nearly ceases, and from there to the region of the pharynx the tubular 

 descending division of the bladder widens considerably. Inside these 

 tubes are to be found many prominent opaque concretions. This part 

 of the bladder was not seen to contract and is thus quite distinct from 

 the muscular tubes of the bladder (lc) and so is designated "Id." 

 The concretions are small at the anterior end, becoming larger and 

 larger until the region of the forking of the intestine is reached, when 

 they gradually become smaller again. These concretions, which T 

 believe to be gradually and continuously formed from the waste liquid, 

 enlarge as they are pushed farther down the eoncretional tubes of the 

 bladder (Id). Why they again decrease in size, I cannot determine. 



