Jensen, Carl Oluf

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Jensen, Carl Oluf

(b. Frederiksberg, Copenhagen, Denmark, 18 March 1864; d. Middelfart, Denmark, 3september 1934)

veterinary medicine.

The son of Peter Jensen, a pipe fitter, and Dorthea Rasmusdatter, Jensen in his boyhood was avidly interested in mathematics and astronomy. In 1882, when only eighteen years old, chance led him to become a veterinary surgeon. He practiced veterinary medicine at Nimtofte in 1883, but he could not earn enough and this fact and illness compelled him to move to Copenhagen, where he began studies under the bacteriologist Bernhard Bang at the Copenhagen State Agricultural College and the Physician C. J. Salomonsen, In 1886, with G. S and, Jensen published a study concerning gas gangrene and the edema bacillus, an anaerobic form which Pasteur in 1877 had erroneously stated to be a septic vibrio.

During the autumn of 1887, Jensen accepted an opportunity to study bacteriology at Koch’s institute in Berlin, and after his return he become an assistant to Bang. In 1889 he was appointed lecturer at the Royal Veterinary and Agricultural College, where he remainded for the next forty-five years: in 1903 he became full professor of pathology and pathological anatomy. In 1890 he married Maria Magdalene Schmit. From 1892 to 1898 Jensen also supervised the small-animal clinic and from 1898 he lectured on serology and serotherapy. Besides developing these new disciplines, he mastered abdominal surgery in the clinic and became the first veterinarian to utilize X-ray investigations in surgery.

In 1909 he founded a serum laboratory, which in 1932 was placed officially under the Ministry of Agriculture, and he continued as its superintendent until his death. From 1898 he was amember of the Veterinarian Board of Health and from 1928 its Chairman. He was appointed Veterinaerfysicus, the highest veterinary office in Denmark, in 1922, succeeding Bang; in 1931 his title became veterinary director, a post he held until 1933. In these official capacities he was able to make effective contributions to the defeat of foot-and-mouth disease in Denmark and toward the export of safer Danish becon to England.

When he became assistant at the college, Jensen continued the investigations begun with Sand. Together they demonstrated in 1888 that strangles, an infectious horse disease affecting the windpipe, was the result of a special type of pyogenic streptococcus, Streptococcus equi. During the following Years he took up the problem of defects in butter-making which led to an unpleasant taste and poor consistency in cream and butter. Inspired by the investigations of Pasteur and Emil K. Hansen of Yeast, Jensen demonstrated the necessity of milk pasteurization and of pure bacterial cultures in butter production; he showed that the noxious bacteria originated in the vessels and tools used in the purification process. In 1891 he published his book on milk and butter defects which enabled farmers to save large sums of money.

In the following year Jensen demonstrated that the bacteria causing swine erysipelas can be found in both the throat and the digestive tract of healthy animals but that with reduced somatic resistance swine contract the disease; disinfection and isolation are then ineffective. In 1892 he found that vaccination with weakened cultures was the only effective prevention. During these years Jensen also investigated infectious diarrhea in cattle and braxy (bradsot), a severe infectious disease in Icelandic sheep. He developed effective serum preparations for these diseases, as well as methods for identification and differentiation of the various bacterial types and races (1897).

With the Nobelist J. Fibiger, Jensen undertook several significant investigations concerning the relation between human and animal tuberculosis—demonstrating, in opposition to the ideas of Koch, that many children are mortally stricken by animal tuberculosis bacteria (1902-1908).

Beginning in 1901 Jensen did experimental work with mice and rats on cancer transplantation; the studies showed that cancer cells survive through generations by transplantation. In 1910 he demonstrated a type of cancerous tumor in turnips, produced by Bacterium tumefaciens (described by Erwin F. Smith). The tumors could be transplanted and survive through generations of turnips not infected with the bacteria.

From 1916 to 1921 Jensen took up an endocrinological investigation, showing that the axolotl, a salamander which normally lives in the larval state and even breeds in this condition, during feeding with a thyroid substance develops to a degree never found in nature. Jensen worked out a standardized methods for the effective preparation of thyroid hormone for medical use (1920).

In 1903 Jensen became a member of the Royal Danish Society of Sciences. He later received the Walker Prize (1906) for his cancer investigations and was created honorary doctor of medicine at the Copenhagen University (1910) and honorary doctor of veterinary medicine at the Berlin Veterinary College (1912). He became a corresponding or honorary member of veterinary societies all over the world. In 1928 he was made president of the Danish Cancer Committee. He founded Maanedsskrift for Dyrlaeger (“Monthly Review for Veterinary Surgeons”) in 1885 and was its coeditor until his death. He died suddenly from apoplexy while on a vacation.


I. Original Works. “Ueber malignes Oedem beim Pferde,” in Deutsche Zeitschrift für Thiermedizin und vergleichenden Pathologie,12 (1886), 31-45, written with G. Sand; “Die Aetiologie der Druse,” ibid., 14 (1888), 437-467, written with Sand; “Die Aetiologie des Nessel—fiebers und diffusen Hautnekrose des Schweines,” ibid., 18 (1892), 278-305; “Ueber derer Aetiologie,” ibid., 21 (1897), 249-274; “Uebertragung der Tuberculose des Menschen auf das Rind,” in Berliner klinische Wochen-schrift,39 (1902), 881-886; 41 (1904), 129-133, 171-174; 45 (1908), 1876-1883, 1926-1936, 1977-1980, 2026-2031, written with J. Fibiger.

See also “Von echten Geschwülsten bei Pflanzen,” 12 conférence internationale pour I’étude du cancer. Rapport (Paris, 1910), pp. 254 ff.; “Om standardisering af thyreoidea-praeparater ved anvendelse af Axolotlr.” in Hospital-stidende,63 (1920), 505-515; Selected Papers, I (Copenhagen, 1948), covering his work from 1886 to 1908; and II (Copenhagen, 1964), covering 1908 to 1934.

Full catalogues of Jensen’s works are printed in Kongelige Veterinaer- og Landbohoiskole 1858-1908 (Copen-hagen, 1908), pp. 555-556, listing his works published between 1883 and 1907; Kongelige Veterinaer- og Land- bohoiskoles Aarsskrift (1919), pp. 295-296, listing works between 1908 and 1918; and Den danske Dyrlaegestand (Copenhagen, 1934), pp. 150-152, listing works between 1919 and 1933.

See also Selected Papers, II, 207-212; Forelaesninger over maelk og maelkekontrol (Copenhagen, 1903), pp. 214 ff.; Grundriss der Milchkunde und Milchhygiene (Stuttgart, 1903), pp. 235 ff., trans. and amplification by Leonard Pearson as Essentials of Milk Hygiene (Philadelphia-London, 1907), pp. 275 ff.

II. Secondary Literature. See M. Christiansen, Selected Papers, I (Copenhagen, 1948), ix-xvi; Oluf Thomsen, “Carl Oluf Jensen,” in Acta pathologica et microbiologica scandinavica,18 , supp. (1934), 9-27;H. M. Høyberg, Den danske Dyrlaegestand (Copenhagen, 1934), pp. 149-152; L. Bahr, “Carl Oluf Jensen,” in Deutsche tierärztliche Wochenschrift, 42 (1934), 161-163; and E. Gotfredsen, Medicinens historie (Copenhagen, 1964), pp. 452, 464.

E. Snorrason

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Jensen, Carl Oluf

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