The Microscope. 101 



as they stain the celloidine. Haematoxylin stains the celloidine also, 

 but if the section be allowed to stand for 24 hours in a weak solution 

 of acetic acid in water (h to 1 per cent.) the celloidine is entirely de- 

 colorized, while the section has a delicate color. Rosin may be used 

 as a contrast color. As clearing fluids, cedar or origanum oil m&y 

 be used, while oil of cloves should be avoided. In using cedar oil 

 the section must be carefully dehydrated. 



ON MAKING SECTIONS OF INJECTED LUNG. 



ARTHUR J. DOHERTY. 



1\ /Tost practical histologists will no doubt concur with the state- 

 -'--'- ment that to cut and mount a really good section of injected 

 lung is by no means an easy task; for, owing to the excessive 

 shrinkage which invariably accompanies the process of hardening the 

 tissue in the ordinary way, the capillaries distributed over the walls 

 of the air-cells present more the appearance of masses of carmine 

 than a fine net- work of vessels, which in reality they are. In order 

 to prevent this shrinkage, I have devised a method of procedure 

 which yields very beautiful preparations, and for this reason an 

 account of the process may be of interest to the readers of this 

 journal. 



The lung is injected in situ through the right ventricle with a 

 stifP, but freely-flowing, carmine-gelatine mass (Dr. Carter's for- 

 mula answers admirably), care being taken to throw the mass in 

 slowly and with a uniform pressure, and not to over-distend the 

 vessels either by injecting too rapidly or for too long a time, i. e., 

 throwing in too much color. When properly filled, the pulmonary 

 arteries and veins are ligatured, the lungs are removed from the 

 body, and are then distended with 90 per cent, alcohol injected into 

 the air-cells through the trachea, which is afterwards to be closed 

 with a clip or "bull-nose forceps." The lungs are then weighted 

 with lead, and placed in a quantity of 90 per cent, alcohol. In 

 twenty-four hours they are taken out, the clip is removed from the 

 trachea, and as much alcohol as possible is drained from the organs. 

 After this, they are to be re-distended with 90 per cent, alcohol, and 

 placed in a fresh quantity of spirits of that grade, just as before. 

 This process is to be repeated on the fifth and tenth days, and at the 

 end of a month the lungs will be found to be well hardened without 

 being in the slightest degree collapsed ; cut fi'om one of the lungs, 

 preferably at the root and transversely across a bronchus, a piece, 

 say half an inch square and quarter inch thick ; transfer it to a 

 glass beaker half filled with methylated chloroform, place the beaker 



