882 DR. F. E. BEDDARD ON 
these proglottids. It should, furthermore, be noticed that while 
the medullary tissue is, as already stated, separated anteriorly 
from the testes, there is no such separation posteriorly where it 
abuts upon the uterus, nor is the epithelial lining of the latter 
apparent in these older ‘proglottids ; thus the transference of the 
eggs into the medullary parenchyma is render ed easier. Finally, 
I have observed that the calcareous corpuscles tend to accumulate 
more thickly where the medullary parenchyma touches the uterus, 
though they are also present elsewhere and in some numbers 
here and there. 
To compare with the above older stages in the growth of the 
sheltering apparatus for, the developing embryos, I have again 
studied younger stages such as is represented in text-fig. 25 of 
my paper referred to*, I have, however, more especially studied 
sagittal sections, as in the case of the older proglottids. In such 
sections there should be visible the origin of the paruterine body, 
were this structure in the genus Oliditenia of the same nature 
as that of Rhabdometra, etc. But I can find no trace of any 
particular condensation and fibrillation of a definite region of the 
medullary parenchyma which might later spread and involve the 
whole region, which is thus inv olved in mature proglottids, but 
for other reasons. 
Not only is there nothing of this kind to be observed in the 
less mature proglottids, but there is no approach towards 
the fibrous appearance of the mature proglottids. This latter 
appearance is, in fact, produced by a new growth, which seems to 
be very remarkable. I have already referred in my account of 
the proglottids of intermediate age to abundant dorso-ventral 
muscular fibres in the medulla; it is, perhaps, to the unequal 
contraction of these by the pr eser vative reagent that the irregular 
outline of the medullar y parenchyma is due, which I have 
commented upon as simulating a paruterine organ of limited 
extent, lying in the medulla ary parenchyma. I now eall 
attention again, In a more particular way, to these muscle-fibres. 
In his account of tapeworms of the subf: amily Avitellinine (of the 
family Anoplocephalidze), Gough f enters in some detail into the 
histology of Avitellina centripunctata, including that of the 
muscular system, which I may conveniently take as a basis of 
comparison with Otiditenia, which shows an important difference. 
Gough points out that the dorso-ventral muscles which traverse 
the medullary parenchyma in that direction, consist mainly of 
bipolar myoblasts with terminal fibrille and, to a less degree, of 
bipolar myoblasts with lateral fibrille. The larger muscular fibres, 
which are tubiform with an axially contained myoblast, are 
limited to the longitudinal muscular layer. My own observations 
upon various genera which I have examined confirm this 
generalisation. The delicate dorso-ventral muscle-fibres of such 
* Loe. cit. p. 202. 
+ Quart. Journ. Mier. Sci. vol. lvi. 1911, p. 347 et seq. 
