872 DR. F. E. BEDDAED ON 



the uterus for this latter reason appeared in an already divided 

 condition. 



It is to be noted that egg-sacs of the character just described 

 occur in the younger proglottids, and that they are also to be 

 found (text-fig. 143, p. 865) in quite young proglottids, in which 

 the ovary and vitelline gland are at their full development and 

 have not commenced to degenerate. Without having any positive 

 proof, I am disposed to tiiink that the cells which encircle the 

 ovum are ovarian or vitelline gland-cells*, which come to be dis- 

 posed round the ovum after the fashion of a follicular epithelium 

 in higher animals. It looks to me, in fact, very much as if a ripe 

 ovum with a few adhei'ent cells moved out into the adjacent 

 parenchyma directly from the ovary. There is here clearly a 

 similarity with the Graaffian follicle of Vertebrates, a similarity 

 which is even increased by the later appearance of a space (perhaps 

 containing fluid) which surrounds the growing ovum. 



It does not always follow that a proglottid which has attained 

 the dimensions and acquired the appearance of a fidly mature 

 proglottid should contain only embryos. On the contrary, as 

 be readily seen from an inspection of text-fig. 146 (p. 870), 

 a large flat pi-oglottid, quite as large as it will grow, may have 

 egg-sacs in many stages of growth. In this figure, which is 

 drawn from a section seen under a low power, the size of the 

 egg-sacs is a rough measure of their relative stages of growth. 

 The largest are of course the oldest, and contain fully developed 

 embryos surrounded by a thick shell and enclosed in rather a 

 large space. Intermediate conditions are to be found between 

 this stage and that in which an undivided ovum occupies all the 

 space of the cavity of the body -parenchyma in which it lies. I 

 have also cut sections of apparently fully mature proglottids, in 

 which there were no advanced embryos. 



This state of afiairs is not unlike what has been described in 

 some other Tapeworms by others as well as by myself. We may 

 exclude Ilonopylidium and Dipylidhim,, which only show an 

 apparent likeness to Eugonodceum. In the former genus, and in 

 certain species belonging to the latter genus, the inclusion of the 

 ripe ova singly in compartments of the medullary parenchyma 

 is preceded by a stage in which a functional uterus exists or 

 [Dipylidnim, various spp.) at any rate a cavity which — fvill of 

 eggs — is ultimately broken up into single compartments. On 

 the other hand, there is a much greater likeness to Eugonodceum 

 in a genus which I have lately described as new under the name 

 of Diplopi/lidiumf. Here we have, as it would appear, no trace 

 of a uterus ; but the eggs are found scattered widely through 

 the medullary parenchyma enclosed in a cavity singly ; the cavity 

 grows in correspondence with the growth of the contained 



* Cf. description of ovarv and vitelline gland above, 

 t P. Z. S. 1913, p. 565, text-fig. 93, p. 566, text-fig. 94. 



