962 SUMMARY OF CURRENT RESEARCHES RELATING TO 



flask ; about the middle of the belly calcareous corpuscles were sometimes 

 observed, and what appeared to be rudiments of suckers were seen on the 

 neck. By the time that seventy hours have elapsed six embryonic hooks 

 were observed on the neck; only a very narrow cavity, filled with fluid, 

 lies between the scolex of the Teenia and the simple cyst which encloses it. 

 There is no definite boundary between the scolex, the cyst, and the " neck " ; 

 and this last may be called the caudal appendage. 



After these experiments with T. murina, which served to convince the 

 author that he had here to do do with a direct development of a tapeworm 

 without the assistance of an intermediate host, he and Calandruccio made 

 experiments with the same Tsenia on six human beings — four adults and two 

 boys. A boy of five years of age, fifteen days after swallowing a number of 

 proglottids of T. murina, had a certain quantity of ova of T. nana in his 

 fasces, and, on being treated medicinally, passed fifty pieces of the latter 

 tapeworm. Although these experiments are not conclusive, they lead to 

 tlie supposition that this worm also ordinarily developes directly, and Prof. 

 Grassi thinks that the same is true also of T. elUptica ; at times they may 

 develope indirectly, and, as the cysticerci of T. mediocanellata are very rare, 

 it, too, may perhaps be another example of direct development. 



Malformed Example of Taenia saginata.* — Prof. C. Grobben describes 

 a specimen of T. saginata taken from a child six years old. Its form and 

 coloration was such as to call to mind Cerehratulus marginatus. The portion 

 examined was found to consist of a broad lower piece, and an upper some- 

 what narrower portion, separated by a constriction, and it measured in all 

 128 mm. There was no sign of jointing, so it was clear that the author 

 had to do with a portion of a Teenia in which the formation of proglottids 

 had not taken place ; examples of this kind of arrest of development has 

 already been put on record by Prof. Leuckart. 



Sensory Organs of Turbellaria-f— Dr. L. Bohmig publishes a pre- 

 liminary account of his investigations on the sensory organs of Turbellaria. 

 In Planaria gonocephala the eyes have a long diameter of about • 18 mm., 

 while the other two dimensions are about • 1 mm. ; each eye has an invest- 

 ment of pigment formed of small blackish-brown spherules, and its convex 

 side is surrounded by a delicate fringe of finely granular protoplasm, in 

 which a number of distinct rounded nuclei can be made out. The presence 

 of them would seem to show that the pigment-covering is derived from 

 several cells, whereas in the eyes of Polyclads there is only one nucleus in 

 the protoplasmic fringe. The so-called optic ganglion consists of a central 

 ball of dotted substance, around which retinal cells are grouped. The optic 

 nerve arises from a part of the brain where the dotted substance is distin- 

 guished by its greater fineness and more homogeneous appearance ; this is 

 the case also in some snails. The cells of the optic ganglion have a large 

 nucleus, and though unipolar, each process soon divides into a number of 

 smaller ones. The end-bulbs are not merely hyaline structureless bodies, 

 but present a longitudinally striated thickening, which is separated by a 

 thin hyaline plate from a finely granular terminal cap. As no lens could 

 be detected, the author suggests that its function is performed by the 

 parenchymatous tissue between the retina and the epithelium, which is 

 viscous and transparent during life. 



Among the rhabdoccelous Turbellaria, the Plagiostomida, which may 

 have four eyes, have these organs more complicated than the Monotidse. 



* Verh. Zool.-Bot. Gesell. Wien, xxxvii. (1887) pp. 697-82. 

 t Zool. Auzeig., x. (1887) pp. 484-8. 



