708 



RECORD OF CURRENT RESEARCHES RELATING TO 



If one reflects, M. Nacliet says, on the necessity of attaching india- 

 rubber tubes to tlie glass taps, and f)f being assured of the perfect 

 immobility of certain anatomical elements, the advantages of the 

 above arrangement will be at once understood. Experiments on the 

 absorption of gas and on the rarefaction and compression of air could 

 not be more simple. The apparatus gives at the same time a moist, 

 a warm, and a gas chamber, and moreover the highest powers can be 

 employed without any inconvenience. The necessary humidity re- 

 quired for the object is maintained by means of wetted blotting-paper, 

 &c., placed in the cell C. 



Fio. :7 



Two parts, as will be seen, are essential in this instrument — first, 

 the moist chamber ; and secondly, the arrangement of the instrument 

 itself. As regards the latter, it is very similar to those of Dr. J. L. 

 Smith and Dr. Leeson,* and the one hitherto made by M. Nachet ; but 

 there is this capital distinction, that the optical ajiparatus in the new 

 instrument is movable in all directions, and that the object remains 

 immovable upon the stage. 



More recently M. Nachet has replaced the cell above described by 

 smaller cells of the same kind attached to brass plates ai'ranged so 



* See Dr. W. B. Carpenter's ' The Microscope and its Eevelatious,' 5tli ed., 

 1875, p. 108. 



