1889.] Microscopy. 747 
ing been guarded to the utmost against diffusion currents. They are 
now to be transferred to borax -carmine, a fluid heavier than t^T) P^^ 
cent, alcohol, by the use of reservoir a'- Fill the long arm of the re- 
servoir with borax-carmine, and cork it, leaving the short arm empty 
and open. Mix equal parts of carmine and 33 per cent, alcohol (call 
this mixture 2). Mix equal parts of 2 and carmine (call this i). Mix 
equal parts of 2 and ^il P^r cent, alcohol (call this 3). Add mixture 
9 to the short arm of the reservoir until it is one-fourth full, mixture 
2 until it is half full, mixture 3 until it is three-fourths full, and fill up 
with II per cent, alcohol. Transfer the object-box and filter to a', 
avoiding bubbles, and uncork the long arm. The flow begins as 
before, but this time upward through the object-box, and the object- 
box, and the objects are thus transferred in from two to five hours to 
After staining, the objects are transferred to 30 per cent, alcohol by 
means of reservoir a, the flow being so regulated that the change takes 
place in from five to ten hours. Then change successively to acidu- 
lated 70 per cent., 90 per cent., and absolute alcohol, allowing five, or 
better, ten hours to each change. Transfer to turpentine, chloroform, 
oil of cloves, or any oil desired by reservoir a'. Finally to thin bal- 
sam, still by means of the differentiator. 
Whenever the objects are to be transferred to a lighter fluid, use 
reservoir a ; whenever they are to be transferred to a heavier fluid, use 
reservoir a'. If objects are to be transferred to glycerine, transfer first 
to 50 per cent, glycerine in twelve hours, and then to pure glycerine 
in twenty-four hours. 
Objects which defeat successful fixation by untimely contractions 
may be rendered insensible by means of the differentiator, and then 
^^^^ perfectly outstretched. Transfer them to alcohol of from 5 to 30 
per cent, (or other paralyzing solution such as chloral hydrate) in from 
two to three hours, when they will be insensible and outstretched, and 
may be fixed as desired. A specially large object-box is easily con- 
trived for larger specimens. 
The differentiator, already in extensive use, was recently invented 
at Naples to overcome shrinkage and contraction in Anguillulids, and 
has speedily recommended itself for a great variety of delicate organ- 
isms, such as diatoms, desmids, and other delicate algse, moulds, 
pteropods, and all sorts of embryological material, and takes its place 
at once as a permanent and very valuable addition to the parapher- 
nalia of the biologist. 
