684 SUMMARY OF CURRENT RESEARCHES RELATING TO 
very thin skin, so that he takes them for gill-like organs. Somewhat 
similar structures are to be found in S. australis. 
R. Nemathelmintlies, 
Development of Organs in Gordiidae.* — Prof. F. Vejdovsky has 
studied G. sestivalis and Gordius Preslii (from Feronia vulgaris ), G. Vseteri 
(also from a beetle), and G. ‘pustulosus. The main object of his investi- 
gation is to show how not only the organs, but their components, pass 
through metamorphoses in the course of development. 
Thus, the well-developed, luxuriant hypodermis of the young be- 
comes a flattened meagre layer in the adults. It degenerates in giving 
origin, first to the outer cuticula, which consists of extremely fine fibrils, 
and secondly to the distinct subcuticula with larger fibres. The fibril- 
lation of the subcuticula is most probably due to a modification of the 
reticulum or so-called spongioplasm. The absence of a circular muscle- 
layer may be correlated with the fact that the hypodermis is certainly a 
muscle-epithelium. 
The origin of the epithelial layer, which gives rise to the longitudi- 
nal muscles, remains unknown. There are two layers of “ mesodermic ” 
cells beneath the hypodermis ; the one forms the longitudinal muscle- 
layer, the other is often called “ parenchyma,” though it is a genuine 
peritoneum lining the body-cavity. The muscle-cells are much flattened ; 
the sarcoplasm or medullary substance is hyaline and homogeneous ; 
the contractile substance runs on both sides of the cell and surrounds 
the pole towards the body-cavity, and there are fine bridges between 
adjacent muscle-plates ; the muscle-plate itself consists of refractive 
corpuscles, and their arrangement gives rise to longitudinal and trans- 
verse striation. 
The young forms show a true body-cavity, and the epithelial cover- 
ing of the muscular layer is the peritoneum ; the parenchyma or cellular 
tissue which is present posteriorly even in the young, and accumulates 
anteriorly into the adult, certainly arises from free lymphoid cells. 
As to the nervous system, Vejdovsky inclines to believe that the 
adult system is independent of the larval, for it is very late in appearing, 
and begins at a considerable distance from the end where the residue of 
the larval body is found. The ventral strand of the young is wholly 
due to a hypodermic thickening, and one of the author’s most important 
results is that the so-called cerebral ganglion is only a continuation. and 
paired swelling of the ventral strand. Strictly speaking, there is no 
cerebral ganglion nor oesophageal commissure, and histologically this is 
corroborated by the absence of the ganglion-cells in the paired swelling 
referred to. In the ventral strand there are three reticular strands, with 
unpaired ganglion-cells and unpaired lateral nerves, while in Lumbricidae 
there are six reticular strands, with paired ganglion cells or groups of 
cells, and paired lateral nerves. 
In connection with the food-canal the author shows that the “ brown 
gland ” opens into the oesophagus, and that the hypoblast cells form, like 
the hypodermis, a muscle-epithelium. 
There are considerable differences, both individual and specific, in 
* Zeitschr. f. wiss. Zool., lvii. (1894) pp. 642-703 (4 pis., 3 figs.). 
