782 SUMMARY OF CURRENT RESEARCHES RELATING TO 



into the oral capsule, a highly complicated organ of fixation, an 

 oesophagus and intestine ; anal glands can only he definitely said to be 

 present in the male. The author concludes with a history of the 

 genital tract, which, well developed in either sex, is remarkably so in 

 the female, where it would appear to be the cause of the greater size 

 of the body. In a transverse section the genital tube may be cut 

 through at least as many as ten times. 



Structure of Trematodes.* — On the lungs of two tigers from the 

 zoological gardens of Amsterdam and Hamburg, Dr. C. Kerbert dis- 

 covered what he describes as a new species of Distomum, D. wester- 

 mani. Two individuals were always found enclosed together in one 

 horny capsule. All the organs of this fluke he has noted with care, 

 and he discusses fully their histological characters. Save that he was 

 not able to trace in his specimens the ciliated funnels at the ends of 

 the finest branches of the excretory canals, as observed by Fraipont 

 in D. squamatum and several ectoparasitic trematodes, he gives in 

 the present memoir a complete account of almost every topic con- 

 cerning the anatomy of trematodes in general. 



Dr. Kerbert resolves the entire body of his Distomum into two 

 strata, cortical and central. The latter is traversed by the dorso- 

 ventral muscles and includes the various internal organs, — nervous, 

 alimentary, excretory, and sexual. 



The cortical stratum includes — the cuticle proper, the epidermis, 

 the basal membrane (" cuticle " of authors), the tegumentary 

 muscular layer, and the layer of tegumentary glands. 



Two kinds of cells make up the splint-tissue constituting the bulk 

 of the central stratum. The first are membraneless, of irregularly 

 rounded figure, with finely granular contents and a conspicuous 

 excentrie nucleus or two nuclei. The other cells are branched ; their 

 branches unite to form a spongy network, in the meshes of which 

 the round cells, usually isolated or in pairs, are included. ' In some 

 places the meshes contain, instead of distinct cells, a protoplasmic 

 residuum with imbedded nuclei. Here and there the trabecules 

 appear under the guise of a very well developed fibrillar connective 

 tissue, with fusiform nuclei among the several fibres. Just under 

 the cortical stratum the cells of this connective tissue blend together 

 into one granular mass of protoplasm, the so-called subcuticular 

 layer. 



As to the several organs, our space only permits us to notice 

 briefly the sexual. These consist of (a) the genital sinus, (b) the 

 male, and (c) the female organs. The genital pore, or common orifice 

 of the whole apparatus, lies in the mid-ventral line, not very far 

 behind the posterior sucker. The sinus itself is lined by a basal 

 membrane, and is an invagination of the cortical stratum stripped of 

 its epidermis. In general form the sinus is conical, with its apex 

 turned backwards and inwards. The apex leads into the female 

 conduit, or so-called uterus. The male opening is situate anteriorly, 

 on the upper wall of the sinus, at its left side. The two, not quite 



* Arch. f. Mikr. Anat., xix. (1881) pp. 529-78 (2 pis.). 



