T^NIA ELLIPTICA. 247 



joints, but I cannot yet follow Leuckart and pronounce tliem to be 

 of sufficient value for specific separation. Until recently, I was in 

 the position of Dujardin, who had not seen this parasite's head ; I 

 have now, however, procured and examined a great number of 

 perfect specimens, and am still unable to pronounce the two forms 

 to be distinct species. Goeze's drawings of T. cateniformis only 

 represent a single row of little hooks ; and it is well known that 

 the same processes in T. cucumerina are very liable to fall off, so 

 much so that it has been described as a hookless tapeworm. Yan 

 Beneden regards the two presumedly distinct forms as identical, 

 and, although his representations of the cephalic hooks of T. canina 

 correspond very closely with those of the T. cucumerina, both of 

 Dujardin and Leuckart, he speaks of three or four rows of hooks, 

 whilst Dujardin says there are three, and Leuckart simply describes 

 a succession (" mit einer mehrfachen Reihe"), though his excellent 

 figure (fig. 118, p. 400, of his work) represents four; he also 

 describes three or four rows as occurring in T. elliptica. It is 

 therefore evident that variations occur in the same form as regards 

 the head ; a,nd it is more than probable that differences of habitat 

 may be sufficient to account for the variations of size and numerical 

 development of the joints, which Leuckart regards as distinguish- 

 ing marks between the elliptic tapeworm of the cat and the 

 cucumerine cestode of the dog. Be this as it may, one or other 

 of these forms has been noticed in the human subject several 

 times ; but as regards the source of their larvee we are yet in 

 uncertainty. When engaged (1856) in rearing Tcenia serrata from 

 Gysticercus pisiformis, I thought I had also hit upon the scolices of 

 T. cucumerina; but Leuckart has since extended my experiment 

 by feeding rabbits with the proglottides of T. cucumerina, without 

 producing any measles. Yan Beneden has also tried to produce 

 the young of Tcenia ellijptica in the rat, but without result. Wein- 

 land thinks the cysticercus of T. cucumerina will be found in ffies, 

 and that dogs obtain the larvae by their interesting habit of 

 snapping at dipterous insects. This, at least, is ingenious. 



