190 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
Th. hrocchi Gr. Probably this occurs only in forms with specially long 
outgrowths. In Th. distinction sp. n. the “ uterus glands ” are unusually 
numerous and large ; their contents are probably masses of sperms ; 
their function is apparently to ensure fertilisation and to absorb the 
superfluous material, whether ova or spermatozoa. The author describes 
six species, three new, with a single male copulatory apparatus, and 
other six, three new, in which the apparatus is double. Of ten other 
species sufficient details are still wanting. The geographical distribution 
of the species is sketched. 
Histology of Cestoda.* — Dr. E. Zernecke finds that the parenchyme 
of these worms consists of multi-ramified connective-tissue cells, the 
protoplasmic processes of which are connected with one another and 
with those of neighbouring cells. These cell-processes are surrounded 
by a sheath of the intermediate substance which is secreted by them, 
and they thus form a network of fine lamellae and fibrils which traverses 
the whole body. These lamellae afford the necessary support to the 
muscles of the parenchyme. Spaces in the meshwork are filled with a 
homologous fluid which does not stain. The Cestoda possess a true 
epithelium, the so-called sub-cuticular cells, of which the cuticle is to be 
regarded as a product. Their muscles all consist of muscle-cells, which 
are referable to the same general type as those of nematodes. They 
partly lie directly on the fibres, and partly are merely connected with 
them by plasmic processes. The innervation of the muscles is effected 
partly by means of the myoblasts, and partly by direct contact with the 
contractile substance. The -excretory vascular system of Ligula is made 
up of an outer and an inner plexus of vessels, which pass into one 
another at the anterior end, and are connected along their course by 
numerous capillaries. Other capillaries are connected with ciliated 
funnels at the sides of the body and at the terminal point. The outer 
plexus of vessels opens by a number of lateral vessels. The nervous 
system consists of a central and a peripheral part. The central organs 
are the longitudinal trunks and the cerebral commissures. In Ligula 
they are surrounded by a proper envelope, possess numerous ganglionic 
cells and lateral nerves which arise by roots. The longitudinal trunks 
of Cestodes are homologous to the lateral nerves of Nemertines and to 
the ventral medulla of Annelids. The peripheral nervous system con- 
sists of sensory and motor fibres and a sub-epithelial plexus. The 
sensory part consists of specific sensory cells under the epithelium, the 
central processes of which end freely in the longitudinal trunks of the 
wall. The peripheral processes are connected with terminal vesicles in 
the cuticle as well as by terminal branchlets ending freely in the epi- 
thelium, the ganglionic cells of which are placed partly in the sub- 
epithelial plexus and partly in a deeper layer. The motor part of the 
nervous system consists of nerves which arise partly from the longi- 
tudinal trunks, and partly from the plexus. The plexus is connected 
with the longitudinal trunks by a number of nerve-fibres, in the course 
of which bipolar ganglionic cells are intercalated. In the cuticle of 
Ligula there are branched cells, the terminal processes of which form 
a basketwork around depressions that appear to be of service in the 
absorption of food. 
* Zool. Jalirb. (Abtli. Anat.), ix. (1895) pp. 92-161 (8 pis.). 
