848 DR. p. E. BEDDARD ON A 



are present — naturally indistinctive. The only way of proving 

 its testicular natvire is the discovery of spermatozoa. An 

 inability to find these is not of itself conclusive proof of the 

 absence of testicular tissue. But an argument of weight in this 

 dii'ection is to be derived from a study of the ripe eggs. These 

 are rather small as compared with some species and possess a 

 very thick hyaline shell, which is with difficulty penetrated by 

 staining reagents. Thus in many of my sections the eggs seem 

 to be simply oval structureless bodies. In cases, however, where 

 the staining has been more successful the true ovum within the 

 shell becomes obvious. It consists of a single cell with a large 

 nucleus. I say a single cell because there ai-e not vitelline cells 

 enclosed within the shell, anything in the nature of a vitelline 

 body being completely absent. The absence of a vitelline gland 

 is rare among tapeworms, but is known in the genus called 

 on that very account AviteUina*. In no case did I find this 

 ovum in course of division — and I have examined a large 

 number of individual ova in many segments. I infer, therefore, 

 that no spermatozoa are formed in this individual worm and 

 furthermore that there is no entry of spermatozoa from another 

 individual — a fact which is also supported by the absence of a 

 vagina. But it must be remembered that the host may not 

 have contained in the bile-ducts another sperm-producing indi- 

 vidual. It may be that fertilisation occurs outside the body. 

 But this is clearly a mere suggestion for the present, though 

 not repugnant to such evidence as there is. 



There being no trace of the actual uterus in the middle 

 region of the body, I naturally sought for these bodies elsewhere 

 and made a series of sections from the anterior region of the 

 body. I selected the rather thicker region which immediately 

 follows the head and examined a piece cut from about 10 mm. 

 behind the anterior extremity. Here, as I imagined, the ■ im- 

 mature uterus might be found or at any rate some trace of its 

 existence, I could, however, find in this part no essential 

 differences from the posterior region of the body which has just 

 been described. The body was in the same way packed in places 

 with the ripe ova, which were pi-esent everywhere in a less crowded 

 state ; indeed, they seemed to me to occur nearer to the external 

 surface here than posterioi:'ly. I found the eggs only just beneath 

 the external cellular layer of the body-wall. The only conclusion 

 that I can come to is that this worm possesses no uterus, or 

 that it exists for a very transitory period only, and also that very 

 possibly the sexes are separated as in the genus Dioicocestus. 

 The specimen described here being a female, this concllision 

 is obviously based upon negative evidence only and is thus less 

 valuable. It is, however, quite clear to my mind that the genera- 

 tive products develop simultaneously in the proglottids and that 



* See Gough, Quart. Jonrn. Micr. Sci. vol. Ivi. pt. 2, 1911, for an account of this 

 genus. 



