BY DR. KLEIN. 171 



Inflammatory Changes in the Liver Cells. Inflam- 

 mation of the tissues of the liver may be induced by passing 

 a needle into the organ. Twenty-four to forty-eight hours 

 after the injuiy, the animal must be killed. The liver cells 

 exhibit distinct appearances of division and germination. 

 Similar appearances are seen in the neighborhood of the so- 

 called psorosperm nodules in the liver of the rabbit. 



Inflammation of the Cornea. Inflammation of the 

 cornea may be studied in the frog in two ways: The cornea 

 may be cauterized at the centre, to such a depth as almost to 

 perforate it, or a thread may be drawn through it entering at 

 the centre and passing out through the sclerotic, beyond the 

 margin, the ends of which are then tied. After cauterization 

 it is necessary to wash the part with a few drops of solution 

 of common salt. In either case the animal is placed in a 

 beaker glass, with some moist blotting-paper at the bottom of 

 it. To study the successive stages of the process, half a dozen 

 corneas should be prepared in this way at a time, which can 

 then be excised after 8, 12, 18, 24, 36, and 48 hours. The best 

 preparations are obtained from rana esculenta, during the 

 summer months, from 8 to 24 hours after the introduction of 

 a silk thread, as above described. The cornea should be 

 studied first in the fresh state, and then stained with gold. 

 It is excised in the manner directed in Chapter II. and pre- 

 pared in humor aqueus, care being taken to protect it from 

 pressure by inserting slips of fine paper under the edges of the 

 coyer-glass. The contrast between a cornea twelve hours after 

 injury and a normal one lies, first, in the immense number of 

 migrating cells it contains, and, secondly, in the marked dis- 

 tinctness of the branched corpuscles. The migrating cells are 

 most numerous towards the periphery, occurring more and 

 more scantily towards the centre. They are masses of proto- 

 plasm of irregular form, beset with knob-like prominences, 

 and exhibit very active amoeboid movement. To study their 

 changes, the preparation must be irrigated with serum. For 

 this purpose, a frog is decapitated and the blood received in 

 a porcelain capsule and allowed to coagulate. The serum is 

 collected in capillary glass tubes. The irrigation is performed 

 as before directed (Chapter I.), a very small strip of blotting- 

 paper being used. Under the immersion objective, the most 

 active motions can then be observed; and if a single corpuscle 

 is kept .under observation for a length of time, it is sometimes 

 possible to make out an appearance as if it were about to di- 

 vide. A line presents itself on the surface, which after a time 

 assumes the character of a furrow. Occasionally the furrow 

 is seen to deepen till the two parts are severed. In other 

 cases, one of the knob-like prominences enlarges and separates 

 itself. As regards the branched cells, some of them appear 



