374 



REPORT OF THE COMMISSIONER OF FISHERIES. 



Table IV. — Showing nitrogen and oxi/gen content {in cnhic centimeters per liter, reduced 

 to 0° C. and 760 mm., dry) of various {J'resh) craters at a)td near fisheries station, 

 Nashua, N. IL ' 



Source of sample. 



Hatchery well No. 1 



Same, second determination 



Same, deaerated drop by drop 



Hatchery well No. 6 



Hatchery well No. 11 



Well in rearing pond No. 3 



Well in rearing pond No. 16 



Reservoir pond water 



Same, through deaerating box 



Creek water, total station flow, aer- 

 ated and deaerated by natural 

 flow 



Largest Pennichuck well, source of 

 Nashua city supply 



Smaller Pennichuck well 



Pennichuck water from service tap 

 at hatchery 



Colerain Brook, a well-aerated nat- 

 ural stream 



Rain water freshly caught 



Actual content 

 c.c. per liter. 



Normal content 

 when saturated 



with air at 

 given tempera- 

 ture, and pre- 

 vailing pressure 

 c. c. per liter. 



Nitro- 

 gen. 



17.5 

 18.1 

 15.0 

 17.8 

 18.6 

 17.5 

 17.9 

 17.2 

 16.4 



17.6 

 18.3 



14.5 

 14.8 



Oxy- 

 gen. 



3.3 

 3.4 

 7.4 

 2.9 

 1.6 

 3.1 

 3.8 

 5.0 

 6.7 



2.1 



2 2 



7.0 



Petters-i 



son and: Wink- 



Son- 

 d6n. 



N. 



16.00 

 16.00 

 15. 35 

 16.14 

 15. 72 

 16.00 

 16.00 

 15. 77 

 15.73 



14.94 

 14.94 



16. 24 



14. 45 

 14. 87 



ler. 



Excess -t- or 



deficit — c. c. 



per liter. 



N. 



8.26 

 8.26 

 7.89 

 8.33 

 8.11 

 8.26 

 8.26 

 8.13 

 8.11 



7. 65 

 7.65 



-1-1.5 



-1-2.2 



-0.35 



-fl.66 



-1-2.88 



-1-1.6 



-f2.0 



-fl.43 



+0.67 



+0. 39 



+2.66 

 4-3. 36 



-0.05 

 -0.07 



-4.96 

 -4.86 

 -0.49 

 -5.43 

 -6.51 

 -5.16 

 -4.46 

 -3.13 

 -1.41 



-1.25 



-5.55 

 -5.45 



-0.39 

 -1.01 



Notes.' — Presumalily normal waters show, according to Tables III and IV, slight nominal excesses 

 or deficiencies of nitrogen, and always a deficiency of oxygen. The.se discrepancies represent limits 

 of accuracy of apparatus and methods as used in the field, and the personal equation. Moreover, 

 saturation "data vary within rather wide limits. 



The figures for the dissolved COo are not included in the tables, as having no particular relation to 

 the present subject. They are considerably higher for fresh water containing a nitrogen excess than 

 for normal water, the former averaging 5.3 c. c. per liter with extremes of 3.6 and 7.4, the latter 1.8 

 with extremes of 1.6 and 2.1. These figures include the semibound carbonate. 



SUMMARY. 



1. Fishes and some other organisms show^ gas symptoms of consid- 

 erable variety and of a pathologic nature. Man}" of these are due to 

 one cause and may be grouped together as a pathologic unit}-, the gas 

 disease. An exophthalmia, or pop-eye, is one of the chief lesions. 



2. Bacteria are not in an}^ wa}" concerned in the gas disease here 

 considered, but may cause similar lesions. 



3. The immediate cause ol death in the gas disease is usually 

 asphyxiation from gas embolism in the gill filaments, or heart, or both. 



4. This embolic gas is due to an excess of dissolved airr in the blood, 

 which ma}^ be immediatel}" caused by a rapid reduction of ]3ressure, or 

 by an excess of dissolved gas in the water, or by a combination of 

 both. 



