974 PROCEEDINGS OF THE SOCIETY. 



i 



Mr. Crisp described, by means of a drawing on the board, Nacliet's 

 improved form of camera lucida with a gold film, which he believed 

 had been seen for the first time in this country at the recent Sanitary 

 Exhibition at South Kensington. 



Mr. Ingpen said he had used one of the same kind for three or 

 four years, with the exception that he had a silver film instead of a 

 gold one. 



Mr. Stewart described a curious appearance of luminosity 

 observed studding the sides of the dark caves and tin-mines in the 

 neighbourhood of Dartmoor. On examination he found it to emanate 

 from a number of small cells filled with a pellucid cell-sap, and con- 

 taining some small chlorophyll bodies. The appearance was that of 

 the emission of a golden-green light, and was apparently produced by. 

 the cells reflecting white light, which assumed a greenish tinge from 

 the colour of the chloroi^hyll bodies. The effect was probably due to 

 a reflection similar to that of light from drops of dew. He believed 

 that these cells were an immature form of moss. 



Mr. Crisp called attention to the explanation of Professor Abbe in 

 regard to the use of two illuminating beams for binocular Microscopes 

 with high powers, whereby advantage was taken of the large effects 

 of parallax presented by wide-angled objectives, while, at the same 

 time, the loss of focal depth attendant upon the wide angle was 

 diminished by one-half (see p. 692). 



The President reminded the Fellows that at their last meeting he 

 had called attention to some silicious spicules obtained from great 

 depths, and had specially referred to some minute canals seen in 

 them, and to some evidence which seemed to show that a minute cell- 

 form had to do with the perforation and enlargement. He confessed 

 to having felt some little doubt as to the derivation of the spicules, 

 although, when things were given to him by a friend, he felt bound to 

 accept the representations made about them. In this case, to make 

 sure, he asked Mr. Moseley to let him have a small quantity of deep- 

 sea soundings, taken during the ' Challenger ' expedition, and he 

 found there not only spicules with these canals, but also the green 

 unicellular substance itself. In corresponding with Mr. Cartel-, he 

 had obtained sufficient information to enable him to venture to write a 

 short paper on the subject in the August number of ' Annals of 

 Natural History.' He found also very clearly that the little pene- 

 trating tubules did not always reach the axial canal, but often ended 

 in a bulb. Of course, this thing must have a name, and so the name 

 Spongiophagus had been proposed for it, and he was very glad to find 

 that Mr. Carter was investigating it. The great interest was as to 

 the manner in which a growth of that kind could absorb the silica and 

 seem to feed upon it ; probably, however, its nutriment was derived 

 from the remains of the organic portions of the sponge. 



Mr. Crisp said that Mr. Carter had recently discovered in some 

 fresh-water forms a Spongiophaga that had not previously been 

 recognized (see p. 901). 



