360 DR. A. E. SHIPLEY ON [ Mar. 16, 
into a peculiarly large and muscular receptaculum seminis, which 
runs across the proglottis and then turns backward; in some 
preparations this turn is seen “en face” and then the radiating 
muscles give the appearance of a ring of very fine spines, and, 
indeed, at first I thought that there was such a ring, but I believe 
the above is the true explanation. ‘There are three testes the vasa 
deferentia of which unite and after entering the cirrus-bulb enlarge 
to form a vesicula seminalis. The vagina opens ventral to the 
penis. The uterus isa single chamber unbranched. It forms a 
conspicuous feature in the hinder end of stained specimens. At 
first it appears as a spherical organ lying in the middle line at 
the hinder end of each proglottis, but as it grows and absorbs 
more of the parenchyma it tends to become triangular or square, 
but always with very rounded angles. It contains a large number 
of relatively large onchospheres or tape-worm embryos (PI. LX. 
fig. 22). According to Wolfthiigel, the embryos measure 0-02 mm. 
in breadth by 0°04 mm. in length. The typical six embryonic 
hooks are very characteristic. The partners in each pair, for 
instance, are usuaily widely divaricated ; their length is 0-014 mm. 
These characteristic Hymenolepis ova have three envelopes: the 
innermost, closely applied to the embryo, is never produced into 
horns; between it and the middle envelope is only a clear fluid in 
which the embryo floats; between the middle and the outer 
envelope are the much vacuolated remains of cells. The position 
of the embryo is eccentric with regard to this outer shell (Pl. LX. 
fig. 22), which measures 0-073 mm. by 0-066 mm. The measure- 
ments are again Wolfthiigel’s. The characteristic hooks are 
figured on Pl. LX. fig. 23. 
We have no information about the fate of these embryos, 
but as a general rule the cystic form of this genus lives in some 
Insect or Myriapod, as is shown by the fact that this genus of 
tape-worm occurs in Bats, Insectivores, Rodents, and Insectivorous 
birds. Hymenolepis nana occurs in man, most frequently in 
children, and is not at all uncommon in Italy. Sporadic eases of 
H, diminuta occurring in man are also recorded. 
We have made and we are making laborious investigations to 
try and discover this second host. In searching for the cysts 
of the Tape-worms we began with the insects which occurred 
most commonly in the crop of the grouse. These we examined 
microscopically, both after teasing the body up in glycerine and 
by grinding it up—but not too finely—in a pestle ; in some cases 
also, as Mr. Fryer* has recorded, sections were made and 
examined, but always without result. 
We were at two disadvantages in hunting for the cysts: 
firstly, we did not know what the cysts of either Davainea 
urogalli or Hymenolepis microps were like; and,secondly, the tissues 
* Interim Report of the Grouse Disease Inquiry. 
