270 CHAPTER XX. 



ganese. According to my experience, this solution is excel- 

 lent, and very often advantageously takes the place of 

 t( normal salt solution." The proportions given are for 

 marine animals, and for terrestrial animals will generally be 

 found much too high. For these from 1 per cent, to 3 per 

 cent, will be nearer the mark. 



392. Iodised Serum. Iodised serum was first recommended 

 by MAX SCHULTZE (Virchow's Archiv, xxx, 1864, p. 263). I 

 take the following instructions concerning it from RANVIER 

 (Traite, p. 76). 



The only serum that gives really good results is the amniotic 

 liquid of mammals. A gravid uterus of a sheep or cow 

 having been obtained (in large slaughterhouses such can be 

 obtained without difficulty), an incision is made through the 

 wall of the uterus and the foetal membranes. A jet of serum 

 issues from the incision, and is caught in a flask prepared for 

 the purpose. Flakes of iodine are then added, and the flask 

 is frequently agitated for some days. Two points should be 

 noted. A perfectly fresh amnios must be taken, for the 

 merest incipience of putrefaction will spoil the preparation. 

 The flask should have a wide bottom, so that the serum may 

 form only a shallow layer in it ; otherwise the upper layers 

 will not be sufficiently exposed to the action of the iodine. 



Another method is as follows : Serum is mixed with a 

 large proportion of tincture of iodine ; the precipitate of 

 iodine that forms is removed by filtration, and there remains 

 a strong solution of iodine in serum. This should be kept in 

 stock, and a little of it added every two or three days to the 

 serum that is intended for use. 



RAN VIE K explains that at the outset serum dissolves very 

 little iodine ; but if an excess of iodine be kept constantly 

 present in the solution, it will be found that after two or 

 three weeks iodides are formed, and allow fresh quantities of 

 iodine to dissolve ; so that after one or two months a very 

 strongly iodised serum is obtained. It should be dark brown. 

 Such a solution is the most fitting for the purpose of iodising 

 fresh serum in the manner directed above, and for making 

 the different strengths of iodised serum that are required for 

 different purposes. In general for maceration purposes a 

 serum of a pale brown colour should be employed. 



