Search

and subsequent experimentation. The same may be said of the streptococcus described by Rosenow.2 The problem of studying this disease in rabbits has been complicated by the appearance of spontaneous encephalitis in these animals which was first described by Bull.3 In recent years, however, this objection has been largely obviated by the work of Wright and Craighead,4 Doerr and Zdansky,5 Levaditi and Nicolou and Schoen,6 Cowdry and Nicholson,7 Goodpasture,8 McCartney 9 and others who have described the microorganism causing this disease. Out of 372 normal rabbits McCartney found as high as 76^ of the animals affected in some groups. The most common lesion histologically consists of focal areas of necrosis near the blood vessels, perivascular infiltration and a layer of mononuclear cells around the focal areas. There are apparently great variations in the lesions and occasionally small areas of epithelial-like cells without mononuclears are found scattered throughout the brain. The histologic lesions in this disease taken together with the clinical course of the disease serves to differentiate it from other forms of encephalitis in rabbits. We have been concerned especially with the form of encephalitis produced in rabbits with the herpes virus. Levaditi and Harvier 10 in 1922 described a form of encephalitis produced in rabbits by an ultramicroscopic virus obtained from a case of encephalitis. Much criticism has been directed against this virus as having anything to do with epidemic encephalitis. Flexner 11 has pointed out that out of thirty sets of specimens from cases of epidemic encephalitis Levaditi succeeded in

Among others Dreyer and Hanssen,1 Kreibich,2 Schmidt-Nielson,3 Burge, Fischer and Neill,4 Vedder,5 and Allen and Ellis6 have exposed ferments, enzymes, proenzymes and hormones to light of short wave length; while Vallet,7 Bayne-Jones and van der Lingen,8 Mayer and Dworski,9 Mayer and Guttmacher,10 , Browning and Russ,11 Cambier,12 Burge,13 Eidenow,14 Weiss and Weiss 15 and several others have exposed living cultures of bacteria and other living cells to the action of ultraviolet rays. Radium too has been employed, for example by Bruynoghe,16 who has reported the absence of lytic principle in the sixth passage of his bacteriophage filtrates when B. typhosus, the sensitive organism used, was previously exposed; and by Brutsaert17 who exposed d'Herelle's P3 to radium emanations equivalent to 0.914 grains of radium for twenty-four hours, and found the lytic property only slightly attenuated. Insulin, according to Ellis and Newton,18 is apparently more active after relatively short exposure to ultraviolet light, losing its ability to produce hypoglycemia only after prolonged irradiation.