98 On the Transport of Uvrrhnf Sjnin-n 



Where a cold storage room is not available, or where the expense 

 involved in its use is considered greater than should be incurred in a 

 preliminary experiment, the cooling may have to be done with ice, and 

 to reduce the quantity of water to be cooled to its smallest limit would 

 be an advantage. Such an end might be secuicd if the cooled water 

 were recirculated. 



For the voyage to NeM' Zealand it was necessary to prolong the 

 period of incubation to oO days. To retard hatching for that time, it 

 was necessary to keep the ova at a temperature of about 35° F. 



The Provincial Cape Government has had under contemplation the 

 possibility of introducing the herring into South African waters. How 

 far it may be possible to acclimatise the herring there is not to be 

 solved a priori. In such matters an ounce of practice is better than a 

 bushel of theory. The only answer to be trusted is that furnished by 

 experiment. And if the experiment can be carried out without an undue 

 expenditure it is well w'orth doing. 



In order that the ova reach Cape Town unhatched they require to 

 be exposed to water of a temperature of from 39° to 46° F. This is the 

 range of temperature ordinarily exhibited by the water of this labora- 

 tory in March. During the voyage the sea-water may have to be cooled 

 down from a temperature of 86° F. 



So far no method has been devised of incubating the ova except in a 

 current of water. I have been able to keep the eggs of the herring alive 

 in stagnant sea-water, a third of which was renewed daily. Some sur- 

 vived for 20 days at a low temperature; the majority was dead by the 

 end of that period; all died without hatching. Similarly some of the 

 ova which were kept in dead moss wet with sea- water, remained alive 

 for 19 days, but they also died, without hatching. It is quite possible 

 that these methods might be successfully developed. That would 

 simplify the problem very much. 



It is possible to keep certain marine animals alive in sea-water that is 

 unchanged duiing a considerable period, all that is necessary being to 

 drive air into the water. The excretory products do not then a])parently 

 seriously pollute the water. Where there are dead eggs piesent. the air 

 current is not sufficient to keep the water in an innocuous condition. 

 The water must be changed : to what extent is a matter for experiment. 

 In the case of artificially spawned eggs it is probably impossible to 

 avoid having some eggs die during incubation, and the dead eggs cannot 

 be readily removed from among the living herring spawn. 



Among the eggs of the hcrriiiL' which wcic incul>at(Ml at this labora- 



