212 m Dublin Microscopical Club. 



jective to contain numerous exceedingly small colourless prisma of 



apatite, as the author supposed. It might be inferred that in this 

 rock the proportion of apatite is unusually large. 



Treble Staining with Picro-Carmine and Iodine Green. — Mr. B. 

 "Wills Kichardson exhibited a cross section taken with the freezing 

 microtome from a kitten's tail, treble-stained with picro-carmine 

 and iodine green, and mounted in Klein's damar solution. He 

 (Mr. Kichardson) observed that sections from the tails of the rat, 

 mouse, or the kitten, when treble-stained successfully, form very 

 beautiful and instructive specimens. In the one he exhibited, for 

 example, there were distinctly differentiated sections of tendons, 

 muscles, hairs in their follicles and even projecting from the opening 

 of each of the exposed hair-shafts, and ossifying cartilage with the 

 recently formed bone. He would not allude to any of the other 

 structures to be found in the section, as they had not been suffi- 

 ciently tinted for satisfactory demonstration with low objectives. 

 Mr. Kichardson further observed that he was experimenting with 

 malachite green as a substitute for the iodine green, and hoped to 

 exhibit some sections from the same tail at the next meeting of the 

 Club stained with the malachite and picro-carmine. Although 

 stainings of animal tissues are not, generally speaking, seen to the 

 best advantage with ordinary artificial light, they may nevertheless 

 be greatly improved by passing the light through thin muffed glass. 



July 21, 1881. 



Periesophageal Membrane of Frog. — Dr. Reuben Harvey exhibited 

 some gold-stained specimens of the pericesophageal membrane of the 



frog. 



The membrane in question is the outer wall of a serous cavity 

 or lymph-space, through which the oesophagus passes. The exis- 

 tence of this lymph-space is not generally known. Although he 

 asked several persons about it, he had found no one who knew it 

 except Prof. Macalister ; and even he was unable to give Dr. Harvey 

 any reference to an account of it. 



Dr. Harvey had discovered the membrane for himself some three 

 years ago. And the following method by which its existence was 

 accidentally made known to him serves to demonstrate its relations 

 excellently. If a sharp-pointed canula be carefully inserted into 

 the oesophageal serosa at either end, but preferably at the upper 

 end, where it is reflected onto the lungs, it is possible to inflate a 

 cavity nearly globular in shape, which shows that the serosa here is 

 really a double layer, there being a visceral layer which is inti- 

 mately bound to the muscularis of the oesophagus, and a free outer 

 layer, which is the membrane in question. The cavity in the case 

 of Mana tempwaria and liana esculentais traversed by few, if any, 

 trabeculae except at the back ; but in the common toad and in 

 Hyla arborea the cavity is so beset with trabeculae as to be hardly 

 discernible. The outer membrane is a very beautiful object for 

 histological work. It is a very delicate transparent membrane, and 



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