196 JOURNAL, BOMBAY NATURAL HLST. SOCIETY, Vol. XXIT. 



water at freezing point (0° C, 32°F.) will at normal atmospheric pressure 

 absorb 19'33 c. c. of nitrogen and lO'lS c.c. of oxygen: as the tempe- 

 rature rises to 20° C. absorption falls to 12'8 c. c. nitrogen and 6'35 of 

 oxygen. 



Certain species of fish of course will not survive in water above a given 

 temperature. Brown trout, for instance, will die in sluggish, shallow water 

 at 70° F, But they will survive comfortably at 72° and over if that water 

 is surcharged with oxygen either with a pump, or by increasing the flow. 

 In other words, the temperature of water affects fish mainly because a high 

 temperature means a deficiency of oxygen. And this explains the fact 

 that it is only with a high temperature that the murrals are compelled to 

 call their air cavities into use. 



The writer has had no opportunity for systematic experiment and tabu- 

 lation of results. But enough has been written to show that a most fasci- 

 nating field of experiment awaits exploitation. For instance : — 



1. Place a murral in a tank minimum temperature 80° F. Time the 



rises for one hour. Raise and lower temperature and note 

 results on the timing. 



2. Prevent fish from rising to the surface at 80° F. : note what period 



passes before he dies. 



3. Prevent fish from rising to surface at 80° F. 



(i) Pump known quantity of oxygen into water and note effect 

 on fish's vitality, 

 (ii) Lower temperature and note point at which fish ceases to 

 show signs of distress. 

 Apart from their scientific interest these experiments will have a practi- 

 cal value. As Mr. Wilson has shown in Madras, murral — one of the best 

 food fishes in Indian waters — are peculiarly adapted to simple methods of 

 pond culture, the main difficulty in connection with them being — in the 

 Punjab at any rate — to prevent their escape during the rains, when they 

 develop most migratory habits. But I know by experience the bitter 

 disappointment of visiting a recently stocked tank to find no sign of the 

 rings indicating that the fish are still " at home. " It will be a great 

 comfort to be able to produce a pocket thermometer and by its aid to 

 decide that the fish are at home indeed, but not rising. At present we do 

 not know the degree of cold which will enable the species to do without 

 its supply of outer air. 



G. C. L. HOWELL, f.z.s.. 



Director of Fisheries, Punjab. 

 loth May 1915. 



No. XIII.— NOTES ON CISSITES. 



E7it. Mo. Mag., Oct. 1902, p. 232. — "On recently opening up a dead tree 

 extensively tunnelled by Xylocopa tenuiscapa, I found the galleries infested 

 by numerous examples of the large red Meloid beetle, Cissites debeyi,¥si\xra.., 

 in all stages. It is said that in Europe beetles of this family deposit their 

 eggs on, or in, the ground, and that the young triungulin larvse attach 

 themselves to some passing bee by which they are introduced into the nest 

 where they undergo their remarkable hyper-anetamorphosjs. In the case of 

 C, debeyi this procedure does not appear to be carried out. I found masses 

 of the eggs actiially in the galleries of the bee, all hatching out into the 



