PROCEEDINGS tonella mwis anemia early in life, between the fourth and sixth week. It then becomes a carrier of the Bwtowlka ~u r i s and possesses an acquired immunity to the infection, The infection following splenectomy in the adult carrier rat is indicative of a depression in the acquired resistance to Bartonella mwis. It has been further shown that the acquired resistance to Trypanosoma; Zewisi of normal rats as a result of a previous infection is uninfluenced by subsequent suprarenalectomy. These observations indicate that once a cellular or humoral immunity is established to an infection or an antigenic substance this acquired resistance cannot be broken down by subsequent suprarenalectomy.Bilateral suprarenalectomy, though markedly depressing the natural resistance of the adult albino rat to toxins, poisons and bacterial and protozoan infections, does not affect the acquired resistaim resulting from previous injections of such substances. Acquired and natural resistance are dependent on different physiological processes in the organism and are not merely quantitative variations of the same process as is generally assumed.

1. The virus of Bartonella muris anemia of splenectomized rats may be transmitted to normal young unoperated rats and rabbits. This confirms the observations of Ford and Eliot. 2. Trypanosoma lewisi infections in normal adult rats are accompanied by an anemia most marked at the height of the infection and the appearance of Bartonella muris bodies in the red blood cells. 3. In young rats Trypanosoma lewisi may produce death from the severity of the anemia, complicating the disease. The anemic virus may be separated from the Trypanosoma lewisi infected blood by passage through young rabbits with subsequent maintenance of the strain in immature rats. 4. A strain of the virus of Bartonella muris anemia capable of producing an anemia in young rabbits and young rats for successive transfers has been isolated from the blood of normal adult unoperated rats by passage through young rabbits. 5. The adult normal rat is a carrier of the Bartonella muris virus. 6. Splenectomy in young suckling rats separated from the mother is not followed by a Bartonella muris anemia. The young suckling rat is not a carrier of the infection.

The resistance of suprarenalectomlzed animals to a number of nonspecific poisons is markedly reduced, as has been shown by several independent workers (1-6). These observers employing such poisons as cobra venom, curare, morphine, diphtheria toxin and typhoid vaccine were able to demonstrate a striking difference in resistance between normal and suprarenalectomized rats. In comparing the results obtained in different laboratories with the same poison, considerable differences in the lethal dose appeared to exist. With some of the poisons, as for example, typhoid vaccine, it seemed likely that the difference could be explained by a lack of uniformity of the preparation. Inasmuch as this test may have considerable value in future experimental work, it seemed advisable to secure additional data concerning certain of these poisons in order to find a stable substance having a relatively constant ratio between the lethal dose for suprarenalectomized rats and that for normal rats. This ratio should be at least 1:20. If such a substance could be found, the test might be standardized. In our attempts to standardize this test, we have used, up to the present time, typhoid vaccine, chloral hydrate, sodium cyanide and histamine, and the results obtained may be summarized as follows:Typhoid Vaccine.--Marine and his coworkers (4) have shown that 75 per cent of rats are killed by 0.25 cc. of a standard typhoid vaccine within 8 days after suprarenalectomy. In a recent paper we showed (6) that suprareualectomized rats surviving in good condition are killed by typhoid vaccine in doses of 0.4-1 cc. at the height of susceptibility (5-7 days). On repeating these experiments, it was noted 5o3 on

Autoplastic splenic transplants were made in adult albino rats 4 weeks and 7 weeks prior to splenectomy and the protective effects against infection with the Bartonella muris anemia observed. 1. One-fourth of the spleen left in situ will protect adult albino rats against the Bartonella muris anemia. 2. Autotransplantation of splenic tissue in adult rats is successful in over 90 per cent of instances. 3. Autoplastic splenic transplants performed 7 weeks prior to splenectomy afford protection against Bartonella muris anemia in more than 50 per cent of instances, whereas 4 week old transplants do not protect. 4. A comparative histological study of the transplants of protected and unprotected rats reveals a regeneration of the pulp cells in the protected rats and an exhaustion destruction of the pulp in the unprotected rats. 5. The reticular cells play a specific rôle in protecting the adult albino rat against Bartonella muris anemia.

In the course of studies in this laboratory on the effect of suprarenalectomy on antibody formation, it became necessary to determine the hemolysin formation in normal rats. The hemolysin formation in several animals, particularly the rabbit, has been thoroughly investigated, but few studies on hemolysin formation in rats have been reported. In relation to a study of the effect of x-ray on antibody formation, Hektoen (1) produced fairly high hemolysin titers in rats with a small single intrapefitoneal injection of sheep cells. Rats present certain peculiarities in immunity phenomena which make such studies of interest. A normal rat produces relatively slight precipitin (2). A state of local hypersensitiveness cannot be induced by injections of a foreign protein (2). Anaphylactic shock is produced with some difficulty (3). Rats withstand huge quantities of various poisons and toxins such as diphtheria (6), tetanus toxin (7) and histamine (4, 5).Method.The blood of the sheep was received in a preserving fluid recommended by Rous and Turner (8), consisting of isotonic solutions of glucose and sodium citrate. Ceils were never kept longer than 6 days in this fluid and control daily fragility tests were employed. The cells used for injection and testing were washed three times with physiological salt solution to which was added .1 per cent of calcium chloride as recommended by Snapper (9) to prevent a disturbance of the osmotic equilibrium between the red blood ceils and the saline solution. Single and multiple injections of varying quantities of antigen were given intraperitoneally and comparative studies of the hemolysin formation were made. Blood was obtained at intervals from the rats by puncturing the heart and withdrawing 1 to 2 cc. of bIood. It was necessary to fix the rat on a board specially constructed and to 713 on