296 SUMMARY OF CURRENT RESEARCHES RELATING TO 



field of observations, pronounce definitely on their use or exact signifi- 

 cance in copulation. 



Peptic Glands of the Superior Region of the (Esophagus in 

 Man.* — M. Gliriski has studied the occurrence and nature of these 

 glands in man. He asserts that, though existing at least in every 

 second person, they are not present in all cases. In from 3 to G p.c. of 

 cases they are macroscopic masses, perfectly visible ; in the rest their 

 presence can only be demonstrated microscopically. They are equally 

 frequent at all ages, and are commoner in males than females. They 

 are usually placed between the level of the cricoid cartilage and the 

 fifth tracheal ring, but occur exceptionally on other parts of the gullet. 

 The large groups may appear lens-like surrounded by a wall, and lying 

 deeply in the gullet, or in round or irregular masses, which may be 

 merged to form larger aggregates, and are slightly raised above the 

 mucous membrane of the gullet. They are usually in two symmetric 

 groups, lying in the side folds ; rarely, in the right side fold a single 

 group occurs. Lying usually on the mucous membrane, they yet some- 

 times penetrate the muscularis mucosa, never the submucosa. Their 

 stroma is a loose lymphoid tissue, which here and there forms lymph 

 nodules. He discusses their significance from a pathological point of 

 view, and suggests that their lymphoid tissue may form the place of 

 entrance of tubercle bacilli. 



Studies in the Retina.f — H. M. Bernard continues these studies, 

 adducing evidence for the continuity of the nerves through the verte- 

 brate retina, through the medium of internuclear connecting filaments 

 between the nuclei of the different retinal layers. This " protomitomic " 

 system has been demonstrated to be continuous with the primitive 

 nerve-fibrillae of the retinal nerve strands. The outermost fringe of 

 the retinal protomitomic system runs down the rods, which are the end 

 organs of the retina as an organ of vision, while the proximal fringe of 

 the same system is continuous with the nerve fibrils. The paper is a 

 very full one, in which the characters of this system are described, as 

 also its relations to the other retinal constituents and to the chromatin 

 of the nuclei. 



Islets of Langerhans of the Pancreas.} — H. H. Dale has studied 

 the pancreas of dog, cat, rabbit, and toad, with reference to the "islets 

 of Langerhans." Laguesse has described a perpetual change of secretory 

 tissue into " islets " and vice versa, the islets being, in his view, pan- 

 creatic tissue in an internally secreting stage, and representing also the 

 stage during which growth takes place. From this view of the normal 

 transformation of the tissues, however, he has resiled, though Dale seems 

 unaware of this. Dale's experiments leave the question of the function 

 of the islets undecided, but the results of occlusion of the duct are in 

 favour of Laguesse's view that they represent an internally secreting 

 stage in the life of pancreatic tissue. 



* Bull. Acad. Sci. de Cracovie, 1003, pp. 740-57. 



t Quart. Journ. Micr. Sci.. xlvii. (190b) pp. 302-62 (3 pis.). 



I Proc. Roy. Soc, Ixxiii. (11)04) pp. 84-5. 



