Biological Survey — Erie-Niagara Watershed 199 



pletecl in the large-mouthed black bass {Aplites salmoides). A 

 more detailed discussion of the problem will be found in that 

 paper. During the summer of 1928 the authors carried on further 

 experimental studies on the life cycle of this tapeworm. The 

 results will be found in the following pages. 



The Adult Tapeworm. — The developmental cycle of the tape- 

 worm was first worked out in part by Cooper^ in which he gave an 

 excellent account of the early growth in the final host, the small- 

 mouthed black bass {M. dolomieu) . At this time he proposed the 

 theoretical life cycle which was subsequently proved correct. This 

 was followed by the suggestion of Bangham- based upon an exam- 

 ination of fish stomachs that a copepod functions as an inter- 

 mediate host. The life cycle was first worked out experimentally 

 by the senior author in 1927. Plate I of this paper is the pictorial 

 representation of the life cycle. The adult tapeworm occurs in the 

 digestive tract with the head or scolex as it is called lodged in one 

 of the pyloric ceca (diverticula of the upper intestine). This 

 worm often reaches a length in excess of that of its host, the largest 

 specimen recorded is one found by the senior author which 

 measured slightly over 750 mm., or 2% feet. The mature prog- 

 lottids (or segments) are found at the posterior end of the chain 

 and are filled with eggs. From time to time the chain breaks thus 

 permitting the proglottids to be passed from the host (Fig. 2). 

 Upon contact with the water eggs are spewed out and gradually 

 settle to the bottom. 



The adult stage of this parasite was first reported by Leidy^ from 

 the rock bass {Amhloplitis rupestris). Later it was found in both 

 the large and small-mouthed black bass as well as the fresh water 

 dogfish {Aynia calva) . Many parasites are found in a single species 

 or at the most are confined to a single genus. In this case there 

 are four different genera which may carry the tapeworm and dis- 

 seminate the eggs of the parasites. This condition clearly com- 

 plicates the problem of control. 



The Eggs. — The mature proglottids which are passed by the 

 bass sink to the bottom. Usually before they settle most of the 

 eggs will have been voided thus spraying them over a wide area 

 (Fig. 2). Typically the eggs appear dumb-bell shaped (Fig 6) 

 although other shapes are recorded (cf Cooper and Hunter). 

 This can only be seen under a microscope wiiich magnifies about 

 350 diameters. Then the six hooked oncosphere (or embryo) may 

 be seen surrounded by its investing envelopes. During the course 

 of the summer the viability of the eggs w^as studied and it was 

 found that the enclosed embryo started to disintegrate after 36 



^Cooper, A. R. Contriliitions to the life history of Proteocephalus amhlop- 

 litis (Leidv). Contr. Caiiad. Biol. Fac. II, fresh water fish and lake biolog\% 

 177-194; pi. 19-21. 1915. 



- Banpfham, R. V. A study of the cestode parasites of the black bass in Ohio 

 with special reference to their life history and distribution. Ohio Jour. Sci.. 

 2.^:255-270; 2 pi. 1925. 



^ Loc. eit. 



