666 



Cancer Research 



that^e teleost thyroid is not encapsulated and 

 that its follicles do not form a distinct organ but are 

 scattered over a wide area. Although the main bulk 

 of the thyroid develops about the stem of the ventral 

 aorta between the first and second gill arches, groups 

 of follicles are not uncommonly found among the 

 adjacent muscle bundles and bone lamellae. This 

 natural arrangement may be erroneously interpreted 

 by the unwary as evidence of invasiveness. 



In a series of papers published in 1910-1914 

 Marine and Lenhart (127-130) reported the results 

 of their observations of this disease among brook 

 trout in a large fish hatchery in Pennsylvania. They 

 denied that the lesion is a carcinoma (128): "In 

 view of the facts that young fish are more affected 

 than old fish, that iodine stops the hN'perplasia and 

 causes it to return to the colloid state, that removal 

 of the fish from the ponds to the open brook also 

 effects a cure, that the clinical incidence of tumors 

 is directly related to the water supply, and that the 

 severity of the disease as determined by histological 

 examination is likewise directly related to the water 

 supply, we cannot accept the prevailing opinion 

 that the disease is true cancer. On the other hand, 

 we believe that the disease as studied by us is an 

 extreme illustration of endemic goiter, the end stage 

 of which is cretinism." The age incidence and de- 

 velopment of the lesion was summarized by Marine 

 (130): "It was found that the thyroid hyperplasia 

 began in the fry as soon as feeding was instituted, 

 and advanced overgrowth was present at the 4th 



month of extra oval life; that the overgrowth pro- 

 gressively increased to the stage of clinical detecta> 

 bility, as ascertained by the reddening of the pharyn- 

 geal floor over the thyroid area, about the tenth 

 month in this hatchery; that visible goiters usually 

 manifested themselves about the beginning of the 

 second year, though they may be present as early as 

 the sixth month, depending on the favorableness of 

 conditions for overgrowth, and progressively in- 

 creased during the second and third years; that 

 older fish were more resistant and tended toward 

 spontaneous recovery." Marine does not deny, how- 

 ever, that the hyperplasia of the thyroid may in 

 some instances progress to actual carcinoma. 



In a recent monograph on the cause of thyroid 

 hyperplasia in animals and man, Duerst (40) ex- 

 pressed the belief that the functional demand made 

 upon the thyroid is in inverse proportion to the 

 oxygen tension of the air or, in the case of fishes, of 

 the surrounding water. He points out that carp and 

 tench require only 3 to 4 cc. of oxygen per liter of 

 water, while trout require 7 to 8 cc. When the 

 oxygen content of the water falls to 3 to 4 cc. per 

 liter the young trout develop thyroid hyperplasia, 

 at l.S cc. per liter they die of asphyxia; whereas 

 carp and tench survive at a 0.5 cc. per liter level. 

 The predominance of thyroid tumors in the Salmoni- 

 dae may be related to the high oxygen demands of 

 these fishes and the low oxygen tension present in 

 the tanks of the fish hatcheries. The fact, noted by 

 Marine, that the goiters occur particularly in young 



Tabu 6: Tbtioid Tdmobi 



Spcdw 

 Lake trout Salmo lacustris (3,000) 

 Brook trout Salteiinui fotUinalis (many) 

 Rainbow trout Salmo gairdntrii (3) 

 Amer. Salmon Salmo solar 

 Trout several wptdt% (several) 

 Trout several q>cdes (many) 

 Trout several species (6) 

 Lake trout Salmo lacustris 

 Trout several q>eciea (thousands) 

 Trout several spedes (thousands) 

 Dogfish Sqiuslut sucklii 

 Sea Baas Strranus scriba k S. cabriUa (5) 

 Barbel Barbus jlupiatialis (several) 

 Trop. Aqoar. Fish Jordandla jioridat (several) 

 Cat&U) CUHai dmmarlii 

 Porsy Bom nrff «rif 



Rainbow trout Salmo goirdnerii (many) 

 Aquar. Fish Daitio atkoUmoaius 

 Aqoar. Fish Bafdoekilus ckaperi (several) 

 Trout qMdct not given 

 S a l iao B ipeciw not gtvco 

 Aquar. Fish Rs^trm UltrUtritta (several) 

 Aquar. Fish BiUrtmifU forwtosa (several) 

 Aquar. Fish Rsibora UioHtkicta (several) 

 Sackfiah Etkmtit ucmeratos (16) 



AnUior 

 Bonnet, 1883 

 Scott, 1891 

 Gilruth, 1901 

 Gilruth, 1902 

 Plchn, 1902 

 Piclc, 1905 

 Jaboulay, 1908 

 H. M. Smith, 1909 



Marine & Lenhart, 1910, 1911, Marine, 1914 

 Gaylord & Marsh, 1914 

 Cameron & Vincent, 1915 

 Marsh & VonwiUer, 1916 

 SchreitmUUer, 1924 

 SchrcitmUUcr, 1924 

 SchreitmUUer, 1924 

 Johnstone, 1924 

 Lcger, 1925 

 RIemm, 1927 

 Klemm, 1927 

 Peyron & Thomas, 1930 

 Peyron ft Thomas, 1930 

 Smith, Coates, & Suong, 1936 

 Smith, Coates, ft Strong, 1936 

 Smith ft Coatea, 1937 

 Luckt ft Schlumberger (not published) 



