PROGRESS IN BIOLOGICAL INQUIRIES, 1921. 



REPORT OF THE DIVISION OF SCIENTIFIC INQUIRY FOR THE FISCAL YEAR 1921.' 



By R. E. Coker/ 

 Assistant in Chnroc of Sci-entific Inquiry. 



CONTENTS. 



Page. 



Introduction 4 



Studies of fishes 5 



The Pacific salmon 5 



Immature salmon in the ocean 6 



Results of marking experiments 7 



Salmon investigation in Yukon River 7 



rhemical studios of salmon ■. 9 



Life histories of marine fishes 10 



Fresh-water fishes • 11 



Whitefislips of the flreat Lakes 11 



Fishes of Wisconsin lakes 13 



The paddlefish 14 



Poisonous action of gar roe 14 



Fishes of tlie Panama regrion 15 



Pacific lierrinc: 16 



Use of fish in conihatin-.' malaria 1(> 



Tooperation in antimalaria campaign 16 



ronditioiis troveniini: ahniidMiice of mosciuito-destroyinjr fish 17 



Mos(|uito control in northern waters 18 



Fish-cultural experiment work 19 



Experiments in propa^'atiii;: and rearing fish in ponds 19 



Water heotles in relation to pond <'ulture 20 



Studies of Salmonida> in relation to fish culture 20 



Miimows in relation to fish culture 21 



A new form of pond outlet 21 



Eradication of some ohiectionable plants 24 



Studies of fish dis(>ase . 2.5 



Mortality in pike-perch eggs 25 



Abnormal conditions of fish ovaries 25 



Disease of rescued fish 26 



Parasitic Hatworms of fresh-water fishes 26 



Treatment of Ichtliyoplithirins dis«'ase 27 



Oceanographic and linmological studies 28 



Investigations in the Atlantic 28 



Survey of Chesapeake Ray 29 



Survey of selected areas in Mississippi River 29 



Studies of inland lakes 30' 



Agar-agar and other gelatins from seaweed 31 



The oyster 32 



Investigations of oyster culture 32 



Effect of pollutions upon propagation of oysters 33. 



Fresh-water nmssels 35, 



Profiagation of mussels 3.7 



Protection of mussels '. 35, 



Miissel survey in upper ^Mississippi River .36'. 



F^xperiments relating to nnissel propagation .30 



Investigations in the Kentucky River 37 



The biological laboratories 37 



' Apm-nrtix VIII to the Report of the U. 8. CommisRioner of Fisheries for 1021. B. F^ 

 Dor. No. »11. 



' With the collahoratlon of the InveKtlpators. 



