MICROSCOPICAL JOURNAL. 209 



dent's (Mr. W. T. Haydon's) address is printed in there- 

 port in full, the subject being- "A Fresh-water Chert from 

 Asia Minor, with observations on its formation and struc- 

 ture, together with some account of the Organic Remains 

 found therein." This is an interesting paper, and suggests 

 many equally interesting directions in which to carry out 

 further investigation. The cherts referred to were "Work- 

 ed Flints" found in a cargo of horse-beans from Smyrna. 

 Several "acknowledged experts" at first pronounced these 

 to be arrow-heads and scrapers, probably of the Neolithic 

 Age ; and there are underlying ironies attaching to the sub- 

 sequent determination that they were really teeth dropped 

 from the old-fashioned threshing-boards still used in Asia 

 Minor to remove the beans from their pods. These cherts 

 were readily traced to their original source, and the paper 

 above alluded to deals with their chemical analysis, and 

 more especially the pains-taking microscopical examination 

 by Mr. Haydon and his friends of the abundant vegetable 

 and animal remains found therein. For this, and for con- 

 clusions drawn by the writer as to their process of forma- 

 tion, we must refer our readers to the original paper, the 

 conclusion being that their origin is mainly diatomaceous. 



Baker's New Achromatic Condenser. — Mr. Chas. Baker 

 has recently submitted for an examination his new achro- 

 matic condenser, which has a N.A. of l*o, and an aplanatic 

 aperture of about "9,being in this respect a great advantage 

 upon the one hitherto listed and sold by this firm, which 

 had an aplanatic aperture of only '65. The power is slightly 

 higher than usual,but not enough to make ita higher-power 

 condenser, whilst we notice with approbation its light and 

 compact mounting. The condenser is fitted with the usual 

 iris diaphragm and ring for stops,but a rotating ring within 

 the latter would be a convenience. The price is $18. 



Embedding. — We have not met with a mixture of stearine 

 and naphthaline for embedding, nor can we find any refer- 

 ence to it in any text-book available, so are not able to give 

 the relative proportions in which the mixture should be 

 made. Can any reader furnish it ? 



