702 



THE ANATOMY OF BOTHRIOCEPHALUS LATUS. 



that most distinctly in undeveloped or only half-developed joints, in 

 which the course of the uterus can often be followed throughout its 

 whole extent. It is only when the ever - increasing mass of ova 

 gradually distends the canal, when the limbs of the loops become not 

 only longer but broader, partly overlapping one another, that the 

 uterus assumes the form of a " rosette," or of a " heraldic lily," which 

 was regarded by the older helminthologists as the most important 

 distinctive character of the species. 



The number of loops, or of " horns " as they are usually, but in- 

 aptly, designated, is in JBothriocephalus usually five (four to seven) on 

 either side. When fully developed they possess a width of about 

 0*5 to 1 mm., and a length of about 2 to 2'5 mm., so that the total 

 length of the uterus is usually between 25 to 30 mm. The anterior 



FIG. 368. Ripe joint of BothrioccpJialus latus with the uterine rosette. ( x 6.) 



horns, though not always the longest, are pretty generally the 

 thickest, and in the older joints are usually distinguished from the 

 others by a dark colouring. They are situated at the sides of the 

 uterine opening and of the cirrhus-pouch, on either side of which they 

 diverge upwards, while the middle horns usually exhibit a more trans- 

 verse course, and the posterior generally diverge backwards. So it is 

 at least when the joints are somewhat strongly contracted. With the 

 increase in length, the various loops shorten and separate somewhat 

 from one another. In assuming a more parallel disposition, the above 

 noted resemblance to the joint of a Tcenia becomes more marked and 

 deceptive, but the absence of a marginal pore prevents the possibility 

 of confusion. The other structures are also affected by the extension, 

 as is shown by the fact that the marginal space free from ova, and 

 especially in front, is in such cases disproportionately large. 



One might be inclined to attribute the looped arrangement of the 

 uterus primarily to the accumulation of ova in the uterus. Such is 

 not, however, the case. The loops may be observed even in imper- 

 fect development, at a time when no ova are present in the uterus. 

 They are rather the expression and result of a growth in length, 



