A field and bacteriological investigation of pseudotuberculosis or caseus lymphadenitis of sheep in Magallanes province is described. A great many isolations of Corynebacterium ovis (Preisz-Nocard bacillus) were made and 15 were studied bacteriologically. Purulence, microbic polymorphism, the affinity for colored solutions and metachromatic granules were sorne of the characteristics and features investigated. In all of the lesions examined, C. ovis could be isolated alone and in 6% of the cases it was associated with Staphylacoccus albus, in 13% with Streptococcus sp. and in 13% with Corynebacterium pyogenes.
The vitality of the stocks of C. ovis was not influenced significantly by the length of the storage period nor by the room or cold-storage temperature. Some of the pathological material were stcired as long as 480 days, others were kept in glycerine up to 170 days, while still others were held at -15°C. for 20 to 60 days and they still retained their vitality.
Because of the importance of the disease, it is suggested that the studies beextended to the southern and central zones of the country.

1 Médico Veterinario del Instituto de Investigaciones Veterinarias