SUMMARY1. Nerve growth factor (NGF) isolated from mouse submandibular gland or from snake venom produced a dose-dependent release of histamine from isolated rat peritoneal mast cells.2. The response was almost totally dependent on the presence of extracellular calcium ions and on added phosphatidylserine or its lyso-derivative.3. At high concentrations, strontium ions could substitute for calcium. 4. The process was non-cytotoxic, relatively slow, pH dependent and blocked by polyclonal antibodies to NGF.5. Binding of NGF to the mast cell was not dependent on added calcium. 6. The release was unaffected by low molecular weight glucose polymers or specific quaternary ammonium salts and thus differed from that evoked by clinical dextran or polyamines.7. The release was not inhibited by soluble rat IgE or IgG and was unimpaired in mast cells recovered from specific pathogen free rats. As such it did not appear to be mediated through interaction with cell-fixed antibodies. The process further differed from anaphylactic histamine release in that there was no accompanying change in the intracellular level of adenosine 3',5'-cyclic monophosphate (cyclic AMP), the activated state induced by NGF was much more persistent than that evoked by antigen, and there was no cross-desensitization between the two latter stimuli.8. In total, these data suggest that NGF may induce secretion from rat mast cells by interaction with a specific receptor on the plasma membrane, possibly similar to that present on sensory and sympathetic neurones.

An improved method for the determination of creatine and creatinine in urine using the Jaffe reaction is described. Accurate results for the determination of creatinine depend upon carefully controlling the hydrogen ion concentration of the reaction mixture, the temperature, and the heating time. The authors conclude that many of the disputes regarding the optimum conditions for the determination of creatine in urine may be resolved in the light of the very marked effect of hydrogen ion concentration.

Severe lameness attributed to osteochondrosis is described in an extensively managed Brahman herd grazing on improved native pasture. Clinical signs were observed in five animals, three of which were necropsied. The most prominent lesions were in the elbow and stifle joints. There were multiple fissuring and ulceration of thickened articular cartilage with numerous osteochondral bodies present in the joint spaces. All affected animals were entire males sharing a common ancestral sire. Inheritance and gender were suspected to be contributing factors in the development of the disease.

Summary Bronchoalveolar lavage samples were collected using a fibreoptic endoscope from horses at specified times before and after single bouts of exercise. Lucigenin‐dependent phagocytic chemiluminescence was used to assess the effect of exercise on the alveolar macrophage metabolic activity in response to stimulation by opsonised zymosan. A profound suppressive effect on the chemiluminescence production was present throughout the first three days after exercise. However, the cellular composition of lavage fluids was not altered by the exercise. It is suggested that strenuous exercise may jeopardise the antimicrobial function of alveolar macrophages which may lead to an increase in susceptibility to infection.

Tennessee Valley Authority, Wilson Dam, Ala. r)iammonium phosphate, produced from anhydrous ammonia and electric-furnace phosphoric acid in a pilot plant using a new, saturator-type process, consisted of aggregates of thin tabular crystals bonded by a film of fine crystals. The product contained 0 to 5% of monoammonium phosphate, but otherwise was substantially free of impurities. Laboratory tests showed the product to be strong enough to withstand ordinary fertilizer handling without excessive degradation, satisfactorily nonhygroscopic, satisfactorily drillable, and suitably stable with r e s p r r t to loss of ammonia by volatilization under normal IllMMONIUM phosphate [(NHJPHPO~; 21.2% nitrogen D and 53.8% phosphorus pentoxide1 has not enjoyed wide usage in this country as a fertilizer; this may be attributed at least in part to the poor behavior of some diammonium phosphate mixtures that have been used in the past and to unfavorable reports on important fertilizer properties of the salt. Most of the diammonium phosphate that has been used in this country wm imported from Germany before World War I1 in the form of granulated nitrogen-phosphorus pentoxide-potassium oxide mixtures (Nitrophoska), prepared by adding a hot concentrated solution of ammonium nitrate to a dry mixture of diammonium phosphate and potassium chloride or sulfate and cooling the mixture in granulating equipment ( 4 , 80). The high initial temperature of the mixture in this procedure was thought to result in some loss of ammonia from diamnionium phosphate (80). ' Most of the Nitrophoslras were characterized by relatively high ammonium nitrate content and nitrogen-phosphorus pentoxide ratio. Therefore, they were hygroscopic and tended to cake and become undrillable unless handled with special care (80). The production of Nitrophoslra from diammonium phosphate was discontinued by the Germans several years ago because of the unsatisfactory physical properties of the product and its tendency to decompose during handling ( I S ) .The properties of diamnioniuin phosphate Chat may affect its use as a fertilizer in this country by itself or in ungranulated mixtures are not well established, although a number of miscellaneous properties of general interest have been reported (5, 6, 9-11, 16, 16, 19, 83'). It is nonpoisonous, nonexplosive, and nonflainmable (it is used as a flame-proofing agent). Several authors have referred qualitatively to the instability of the salt, Collings (8) stated that. it has not been used as extensively as the monosalt "because of its unstable nature and its poor physical condition." Ross, Mehring, and Merz (1'9) observed that it loscs ammonia when moistened with water and concluded that for this reason, and because i t is less convenient t o prepare than t,he monosalt, it would find limited application in this country unlcss mixed with acidic materials. Mehring and Cumings (1.5) reported that it lost ammonia and bcc:tnie paqty when exposed to 1 Present address. Mississippi Chemiual Corporation, Leland, Miss. * Present a...