84 



the fact that a reticulated etructure was shown by grinding, to convince him 

 that such was the case. 



Mr. Waller said he was very much interested in the subject of sponges, and 

 his belief was that sponge had a great deal to do with flint structure, although 

 he might say that his opinion was formed in a somewhat rough and ready 

 manner. 



The President asked if Mr. Johnson thought it was the animal matter in his 

 specimens which was affected by the staining fluid, and asked if he had brought 

 any slides for exhibition ? 



Mr. Johnson thought it was the silica which was stained. He had not brought 

 any slides with him, but would do so at the next gossip night. 



The President could hardly, for his own part, see how flint could receive a 

 stain ft'om such a substance as the die employed. 



Dr. Foulerton thought it was very interesting to find a definite structure in 

 these substances, but he was of opinion that what Mr. Johnson had to do was 

 to give them a reason why this structure was a sponge. 



Mr. Lowne said that if sufficient] time were given anything would stain. Flints 

 were constantly met with stained with oxide of iron, and sections of these had 

 very much the appearance of containing pieces of sea-weed —moss agates were 

 instances well known. He knew of no mineral which stained more readily than 

 silica. He thought they ought, before deciding, to have some definite charac- 

 teristic of sponge shown. He saw some resemblance to sponge structure in the 

 drawings, but did not recognise any character which he considered conclusive. 



Mr. Johnson said that he did not know that he had ever stated positively that 

 the structure he found was sponge. .All he had affirmed was that it was an 

 organic structure. 



Dr. Foulerton asked if Mr. Johnson could give them a specimen about which 

 there was no doubt as to whether it were a sponge or not ? 



Mr. Johnson said he could not. He thought it was clear that a substance 

 might be organic, and yet not be a sponge at all. 



Dr. Foulerton suggested the resemblance to those organisms which were found 

 in fossil teeth. 



Mr. Johnson said fossil teeth might be filled with other organic substances ; 

 it was quite clear that a dental foramen would afford a passage into the tooth, 

 and where fungi could go a sponge might go. With regard to the facility of 

 staining flint, if Mr. Lowne did not know of any mineral which stained more 

 easily, he could tell him of a good many. 



Mr. Lowne said he meant any mineral of equal hardness or compactness. The 

 fact that sponge gemmules had been found in flint, and^had not been found in 

 other minerals was, he thought, rather a cause for hesitating before pronounc- 

 ing an opinion. 



Mr. Waller said he had examined a great number of sponges, in which he 

 could not find any gemmules at all— to find them the sponge must be examined 

 at a particular period of its existence. 



Mr. Johnson thought it would be rather hasty for any one to come to a con- 

 clusion at all upon a thing which he had not seen ; he would therefore endeavour, 

 at the next meeting, to bring some specimens, which he hoped would throw 

 some light upon the matter; He himself thought that if a substance, apparently 

 homogeneous, was found to reveal structure when carefully examined, there was 

 a great probability that it was of organic structure, but he did not mean to say 

 that all these structures were sponge. Some flints were naturally found with 



