EXPERIMENTS WITH TAPEWORMS. 

 I. SOME FACTORS PRODUCING EVAGINATION OF A CYSTICERCUS . 1 



JOHN W. SCOTT. 



During the past winter the opportunity came to me to try a 

 series of experiments upon the bladderworm stage of Tcenia 

 serrata, one of the common dog tapeworms. The work was 

 made easy because an abundance of material could be secured 

 from the cottontail rabbit in this vicinity. As I have found 

 no record of previous experiments of this kind, it has occurred to 

 me that a brief account of them might be of general interest. 

 One series of experiments in particular I shall here present for 

 consideration. One of the methods used makes it possible to 

 study the process of evagination in the living animal, and to 

 readily secure evaginated cysticerci without the formality of 

 passing them into the intestine of the host. 



Tcenia serrata is interesting historically from the fact that it 

 was the species first used to demonstrate the characteristic life 

 history of a cestode. Kiichenmeister took the bladderworms, 

 known as Cysticercus pisiformis Zeder, from the body cavity of 

 hares and rabbits and fed them to dogs. In the course of two 

 to three months he found they transformed and developed into 

 the adult Tcenia serrata, so that proglottides were detached and 

 lost in the fseces. When the eggs of these forms were fed to 

 hares or rabbits, after the second day of the experiment, minute 

 whitish cysts were discovered in the liver tissue. Subsequently, 

 in about thirty days these parasites left the liver and developed 

 into the full grown Cysticercus pisiformis. It is to be noted that 

 this life history involves a parasitism in two entirely different 

 hosts. In general, in the first of these hosts the young tape- 

 worm reaches a stage in development known as a Cysticercus, 

 and usually comes to rest in some particular tissue or part of the 

 host's body. But in order to continue development it must be 



1 Contribution No. 5 from the Zoology Laboratory of the Kansas State Agri- 

 cultural College. 



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