424 PROCEEDINGS OF SOCIETIES. 



Artificial Production of Crystals of Oxalate 0/ iwrae.— Professor 

 Tichborne showed some artificial crystals of oxalate of lime. These 

 were of various shapes, but the well-known typical crossed octohedra 

 were there in great abundance. The point of interest in connection 

 with them was the ease with which they could be formed. A deep 

 glass was taken, into which was placed a very thin layer of a satu- 

 rated solution of chloride of calcium and a piece of marble ; floating 

 upon this was put a considerable depth of glycerine, and again on 

 the surface of this a weak solution of oxalate of ammonia ; the 

 whole was then placed on one side in a situation where it would not 

 be disturbed for a space of two months. Diffusion of the liquids 

 took place, and on examination a fine crop of this crystal was found, 

 capable of being mounted in the ordinary manner. 



The Connection of tie Peritoneal " EndotJielial" Cells. — Mr. 

 B. "Wills Eichardson exhibited several preparations of bis own 

 mounting to illustrate the connection of the peritoneal " endo- 

 thelial" cells with one another. The specimens were prepared after 

 the nitrate of silver process, which had been very successful. The 

 so-called cementing substance connecting the margins of the endo- 

 thelial plates with one another was almost black, having the appear- 

 ance of a beautiful network. This was very well seen on the under 

 surface of the abdominal wall of the mouse and in the peritoneal sur- 

 face of a rabbit's bladder. The preparations were submitted to the 

 action of the nitrate of silver solution (one grain of nitrate to every 

 drachm and a half of distilled water) for two minutes, then carefully 

 washed in distilled water, and afterwards submitted to the action of 

 bright sunlight for about one minute, when they were ready for 

 mounting in glycerine. — Mr. Eichardson also exhibited a carmine- 

 stained piece of the desquamated epithelium of the frog, and 

 observed that he had failed in staining the cementing substance 

 connecting the cells together with the nitrate of silver ; at least the 

 nitrate would not differentiate this substance by tinting it of a 

 darker colour than the cells. 



On the Structure of Anorthite Dolerite. — Professor Hull, F.E.S., 

 exhibited a translucent thin slice of anorthite dolerite from Carling- 

 ford mountain, which was apparently similar in structure and 

 composition to the dolerites of the north of Ireland, except that the 

 usual labradoritefelspar was replaced by anorthite. The determination 

 of this felspar had been made by the Eev. Professor Haughton, who 

 found, from the large proportion of lime, that it was anorthite, 

 which he attributed to its proximity, when in a state of fusion, to 

 the carboniferous limestone of the district. In composition it con- 

 sists of a base of augite, in which the felspar is very definitely de- 

 veloped in the form of distinct cry.stals, or groups of crystals; with a 

 low power, and under polarized light these display a very rich plav 

 of colours, some of ruby tint being particularly beautiful, while the 

 parallel bands and fine lines, characteristic of the triclinic group of 

 felspars, are strongly pronounced. Along with these are a few 

 opaque grains of magnetite, and one or two large rounded grains, 

 with a fainter play of colours than in the case either of the felspars 



