892 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Anatomy of Sipunculus nudus.* — Dr. J. Anclreae publishes a 

 preliminary notice of liis studies from which we learn that the 

 tegumentary glands are either bi-cellular or multi-cellular ; in either 

 case they are invested in a delicate membrane and open to the exterior 

 by a more or less long efferent duct. In the first the two contained 

 gland-cells are hemispherical in form, having their flat sides applied 

 to one another ; in the centre of the whole gland there is, however, a 

 wide cavity between the two which is continuous with the efferent 

 canal. In the multicellular glands, on the other hand, the cavity 

 within the gland-envelope is traversed by a fine fibrous network, in 

 the meshes of which are to be found elongated pyriform cells, and 

 these, unlike the cells of the other form, are distinctly nucleated. 

 Terminal sensory organs are irregularly scattered over the whole 

 surface of the body, and consist of a large number of modified hypo- 

 dermal cells, set in palisade fashion ; in addition to these there are 

 glandular organs which are connected with nerves. The histological 

 elements of the musculature are fine elongated spindle-shaped fibres 

 in which a thin hyaline sarcolemma, a delicately fibrillated mass, and 

 a granular cord running in the axis of the fibre are to be made out. 

 The musculature is closely connected with the true integument, along 

 the lines of the longitudinal muscles ; between these the skin is free, 

 and so we have formed the tegumentary cavities. When subjected to 

 microscopical examination the ventral cord was found to have a 

 double investment of layers of connective tissue, which were separated 

 from one another by a pretty considerable space ; this last is not, ks 

 has been often supposed, a blood-vessel, but it is an essential part 

 of the cord, and is filled up by a finely granular mass, in which are 

 imbedded well-marked nuclei and a number of pigment-spheres. 



Development of Tricuspidaria nodulosa.t — P- Megnin here 

 gives a somewhat fuller account of his researches.^ In speaking of 

 its migration from one part to another of its host, he states that it 

 frequently seems to lose its way and to fall into the peritoneal cavity, 

 when it will perish unless saved by the tooth of a carnivore more 

 powerful than its host. These peritoneal Trioenophora, which lose 

 their tricuspid spines, are the Ligula nodosa of the earlier helmintho- 

 logists, and, in their asexual condition, the embryo, according to 

 Bertolus, of Bothriocephalus latus. 



The adult seems to attain the length of 10-15 cm., with a breadth 

 of 0" 5 to 4 mm. ; the tail end is often discoid in shape. 



Development of the Trematoda.f — We have here a notice of 

 Prof. G. B. Ercolani's work on this subject, illustrating the process 

 of the adaptation of an individual to the surrounding medium. The 

 subjects of study were the imj^ortant forms Distonmm hcpaticum and 

 D. lanceolatum ; and the author shows that the same Cercaria or embryo, 

 if developed in two different media or animals, alters its specific 



* Zool. Anzeig,, iv. (1881) pp 477-81. 



t Joiiin. Anat. et rhysiol. (Robin), svii. (1881) pp. 419-26 (1 pi.). 



X Sec this Journal, ante, p. 604. 



§ Joura. Anat. et Physiol. (Robin), xvii. (1881) pp. 434-6. 



