ON AN EASY AND CERTAIN METHOD OF 

 HATCHING CEUATODUS OVA. 



By THOS. L. BANCROFT., M.B. Edin. 



Read before the Royal Society of Queensland, April 29, 1913. 



Hitherto only a very few of the Ceratodus ova obtained 

 each season hatched out* and it was generally considered 

 by myself and others, who have made the attempt, that 

 the ova were easily injured by handling or that strong 

 light quickly killed them or that a large proportion were 

 infertile, that it was essential for success to keep them 

 in running water or the water changed for fresh every day.. 



Semon in his work " In the Australian Bush," p. 90, 

 says : — " The eggs of Ceratodus are extremely frail and 

 tender. If the water in which I kept them for breeding 

 purposes became too warm or there happened to be too 

 many in one vessel or if I did not take care to remove 

 every dead egg immediately, all the eggs died off rapidly. 

 This circumstance formed a great hindrance to my embryo- 

 logical collecting." 



Having made the discovery that when more than 

 three ova were placed in the same glass jar all of them 

 perished, and that with two or three ova success occasionally 

 followed ; it occurred to me that if each egg could be kept 

 separately in a jar of water of its own, any that were then 

 alive would probably develop. For this purpose I gathered 

 together over a hundred pickle botties, filled them with 

 river water and placed each bottle inside a jam tin to exclude 

 light, old rusty tins from the rubbish heap were requisitioned ; 

 the tins with their bottles were placed on and under a 

 table in a corner of the verandah and screened from the light 



* Proc. Hoy. Soc. Queensland Vol. xxiii., p. 251. 



