Make a solution (_1_) by adding 30 cc. of _a_ to 12 cc. of _b_, and a solution (_2_) by adding 24 cc. of _c_ to 60 cc. of _a_; both mixtures to be made at a temperature of 30°C. At same temperature add 24 cc. of _d_ to solution _2_, and then solution _1_, stirring constantly so that Berlin blue is precipitated. Heat on a water-bath to 90°C.; filter through flannel. 3. =Fischer’s Milk-Method.= The vessels are flushed with 8 per cent sodium nitrate or sulphate solution, and then injected with milk. When sufficiently injected the tissue is hardened for 24 hours in a solution of water, 1,000 cc., formalin (40 per cent formaldehyde) 75 cc., and glacial acetic acid 15 cc. Freeze, cut and stain with Sudan III or Scharlach R.; the course of the vessels is outlined by the fat-globules. 4. =Silbermann’s= method of injecting indigo-carmine, eosin or phlosin-red into the circulating blood has been used for the demonstration of capillary thrombi, the latter remaining free from the pigment. 12. =Warm Stage.= For the study of vital phenomena in the living cell _Ross’s electrical warmer_ is recommended. It can be slipped on and off the slide without changing the focus, and is managed without any difficulty. It keeps the centre of the slide at a temperature of 37°C. Reagents can be applied as desired. Deetjen’s agar may be used as a medium for the preservation of living cells. (See Methods of Blood-Examination.) Various forms of warm and moist chambers used in experimental embryological work can also be utilized in experimental pathology. 13. =Tissue-cultivation.= The embryologic methods of growing tissues in lymph and blood-plasma as developed by Harrison, Burrows and Carrel have been applied in pathologic work to the experimental study of repair and regeneration, grafting, transplantation and tumor-transplantation. (For methods see _Harrison_, Journal of Exper. Zoology, 1910; _Burrows_, Jour. of Amer. Med. Assoc., 1910; _Carrel_, Jour. of Amer. Med. Assoc., 1910.) II. REAGENTS USED IN THE EXAMINATION OF FRESH TISSUES.