experiment, however, in which three pairs 

 were provided with small barrels in which 

 they could spawn. Two of the three pairs 

 spawned and each pair used the barrel. 

 Both facilities were in the holding house 

 of the U. S. Fish Cultural Station, Tisho- 

 mingo, Oklahoma, where workers and visitors 

 frequently passed them. Each facility was 

 supplied with flowing water. Tar-paper 

 mats were placed on the bottom of each 

 aquarium so that the eggs could be easily 

 removed to a mechnical hatching trough. 



COLLECTION, PRESERVATION, AND 

 STORAGE OF PITUITARIES 



Pituitaries of carp (Cyprinus carpio ), 

 buffalofish ( Ictiobus spp.), flathead cat- 

 fish ( Pilodictis olivaris ), channel catfish 

 ( Ictalurus punctatus ) , and gar ( Lepisosteus 

 spp. ) were used to induce spawning in chan- 

 nel catfish. Several other species were 

 used, but the limited data do not permit 

 positive conclusions other than to suggest 

 that the pituitaries of the fresh-water 

 drum ( Aplodinotus grunniens ) and river carp- 

 sucker ( Carpiodes carpio ) may be inactive 

 or have low gonadotropic activity in channel 

 catfish. 



The fish from which the pituitaries 

 were obtained were not classified as to sex 

 and state of sexual maturity, but the month 

 of collection was recorded. Only those 

 fish believed to be large enough to be sex- 

 ually mature were used as donors. The 

 minimum size of the fish approached the 

 adult size as determined by age and growth 

 studies of fish in Oklahoma. Small fish do 



Figure 3. — ^Male channel catfish can be distinguished from the 

 female by the tubular nature of the external genitalia. 



not yield a pituitary of sufficient size to 

 make collection worthwhile. 



Pituitaries were removed and placed 

 in acetone soon after death of the donor to 

 prevent enzymatic deterioration of the 

 gonadotropic hormones. Four changes of 

 acetone in the ratio of 12 of acetone to 1 

 of pituitaries 12 hours apart were suffi- 

 cient for dehydration. After dehydration, 

 the acetone was decanted and the pituitaries 

 were air dried and stored in vials in a 

 cool, dry place in the laboratory. Pitui- 

 taries properly collected and dried retained 

 their activity for at least a year (our 

 longest data period) and according to 

 Hasler, Meyer, and Wisby (1950) for as long 

 as 10 years. Presumably they will last 

 much longer, but data are not available at 

 present. For other methods of handling 

 pituitaries, see the review of Pickford and 

 Atz (1957, pp. 264-265). 



USE OF PITUITARIES 



Preparation and Injection 



The pituitaries were weighed, finely 

 ground, and mixed with either distilled 

 water or physiological saline. Usually the 

 carrier was distilled water to which peni- 

 cillin-G was added. Each female was 

 injected with about 1 cc. of water, 10,000 

 units of penicillin, and the appropriate 

 amount of pituitary material. In the early 

 experiments before we used penicillin, in- 

 flcimmatory abdominal lesions were common. 

 These peritoneal lesions led to intestinal 

 auihesions and often to infections which 



resulted in the death of the test 

 fish. Similar results have been 

 reported by Pickford (Pickford and 

 Atz, 1957, p. 265) when unfiltered 

 suspensions of acetone-dried pitui- 

 teiries were used. However, when we 

 included penicillin, no inflzunma- 

 tion resulted even after 20 or more 

 injections. Other eintibiotics, 

 such as dihydrostreptomycin, S-R-D 

 (a mixture of penicillin and dihy- 

 drostreptomycin), and tetracin were 

 occasionally used, but our data are 

 not sufficient to prove that any of 

 these is superior to penicillin-G. 

 The technique otherwise was not 

 sterile. Usually the pituitary 

 material was injected into the body 

 cavity immediately behind a pelvic 



