214 MR. p. E. BEDDARD ON A 



different appearance. It is much more distinctly fibrous than in 

 younger pi-oglottids, as is plainly shown in the text-figure just 

 referred to. The fibres run, on the whole, dorso-ventrally, and 

 thus appear transverse in sagittal sections. The fibrous appear- 

 ance of the parenchyma is particularly obvious where the fibres 

 are frayed out, owing to the breakage of the section. In such 

 sections the calcareous corpuscles are still quite plain, chiefly 

 massed posteriorly in each segment. And, finally, in proglottids 

 of this age the uterus retains the perfect regularity of its shape. 



We may now revert to the ripe detached or quite easily detach- 

 able proglottids. The same fibrous appearance of the medullary 

 parenchyma is plain ; but, owing to the swelling of the whole 

 proglottid, the fibres no longer run entirely transversely in a 

 dorso-ventral direction, but tend, in places at least, to be more 

 circular in the way in which they lie. 



This is especially the case in the neighbourhood of the uterus. 

 In these segments, however, we can no longer speak of a uterus 

 like that of the earlier proglottids represented in the series of text- 

 figures already dealt with (text-figs. 24-29). In the completely 

 mature proglottids (text-fig. 30) under consideration the embryos 

 are in partly or wholly detached masses of roughly spherical form 

 consisting of more or fewer individual embryos. These spherical 

 sacs, though of course vestiges of the uterus, seem to have no 

 definite walls of their own, but to be bounded only by the fibrous 

 tissue of the medullary parenchyma. There are comparatively 

 few of them, and those so small as to contaih only one embryo are 

 very few. The spherical masses of embryos are encii-cled hj the 

 fibres of the medullary parenchyma in such a way as to pioduce 

 the impression of a definite sheath, which is perhaps particularly 

 obvious in the case of two such masses lying close together. This 

 statement applies to the larger as well as the smaller masses of 

 ova. There is not, however, any very great development of this 

 sheath, the character of its fibi'es being quite like that of the 

 surrounding parenchyma. Otherwise, we might speak of par- 

 uterine organs ; and, in any case, it is to be pointed out that we 

 may have here just the commencement of the formation of 

 paruterine organs, which is carried much further, but along the 

 same lines, in such a genus as Thpsanotcenia* . I take it, how- 

 ever, that there is nothing sufficiently definite to allow of the 

 assertion that the present genus or species is to be characterised 

 by the possession of paruterine organs. Before comparing the 

 history of the development of the uterus in this species with that 

 of other forms it will be necessary to follow the development of 

 the contained eggs. 



In the uterus, when in such a stage of development as is 

 represented in text-figure 24, there are comparatively few eggs. 

 In many sections the cavity of the uterus, which is not yet very 

 spacious, is seen to be completely empty. When ova are present 



* See Beddard, " On Two Genera of Tapeworms," P. Z. S. 1911, p. 994. 



