154 



PROGRESS OF MICROSCOPICAL SCIENCE. 



in recent Foraminifera,, immediately surrounds the cliambers (sec 

 Fig. a a). It is not a layer of chrysotilc aciculse, as asserted by Pro- 

 fessors King and Eowney, but is a calcareous lamella, perforated by 



This represents a vertical section of a portion of one of the calcareous lamellre 

 of Eozoon canndense, showing the tubular "nummuline layer" a a, the "inter- 

 mediate skeleton " c c, and the relations of the origin of the canals 6 i to the 

 tubuli of the nummuline layer, the flexures of which are seen along the line 

 a' a' : 100 diameters. 



minute tubuli, which usually lie straight and parallel, but are often 

 more or less curved. These tubuli, like the chambers and canal-system, 

 are usually filled with serjientine, which has passed into them from 

 the chambers in which they originate ; and thus it happens that the 

 original tubulation is generally obscured, being only represented 

 microscopically by the difference in refractive index between the 

 calcareous shelly layer and the serpentine which has filled its tubes, — 

 just as in a specimen of fresh bone or dentine mounted in Canada 

 balsam, the tubuli are only represented by the different refractive 

 indices of the matrix and the balsam. But in the specimen of Eozoon 

 figured above, many of the tubuli remain empty ; and tJiey can be dis- 

 tinguished as tubuli under any magnifying poioer that the thickness of the 

 ■covering glass alloivs to be tised. Further, they have the somewhat 

 sinuous course of the tubuli of organic structures ; and they present, 

 at what was probably a plane of interrupted growth (a a'), the sharj) 

 flexures which Professor Owen first pointed out in the tubuli of den- 

 tine, and which I described and figured twenty-seven years ago in the 

 hard dentine-like substance of the end of the Crab's claw."* 



And after some further remarks a propos of the histological 

 powers of his opponents, Dr. Carpenter says : — 



" I now pass on to a second probative fact of at least equal 

 cogency, — the relation exhibited in the same specimen between the 

 ' canal-system ' and the tubuli of the ' nummuline layer.' 



* Eeport of the British Association for 1847, i^l. xx., fig. 81. 



