1887.] On a Balanoglossus Larva from the Bahamas. 473 



An electric spark of low tension not capable of igniting the unin- 

 duced explosive mixture invariably does so, after the vibrating has 

 been set up. 



It is suggested that the tremor sent through the unignited gas 

 synchronised some of the molecular vibrations, so that the molecules 

 capable of reacting perform their translatory movements in some 

 measure together, and that when a focus of inflammation is present 

 more reacting molecules come into the sphere of inflammation in a 

 given time, and therefore the rate of inflammation is more rapid. 



XXX. " Note on Communication entitled 4 Preliminary Note on 

 a Balanoglossus Larva from the Bahamas' (' Roy. Soc. Proc.,' 

 vol. 42, p. 146)." By W. F. R. Weldon, M.A. Communi- 

 cated by Professor M. Foster, Sec.R.S. Received June 16, 

 1887. 



In a paper, communicated to the Royal Society in March last, I 

 described a series of Balanoglossus larva?, found by me in the Bahama 

 Islands. The series extended from a larva with one pair of gill- slits 

 to a form resembling in many ways a normal Tornaria ; but the dif- 

 ferences between this larva and the normal European form were so 

 great as to induce me to believe that a process of degeneration was 

 going on, and that the Tornaria-like creature was the oldest, not the 

 youngest, of the series. 



On seeing my paper, Professor Spengel, whose researches on 

 Balanoglossus are well known, wrote to me, informing me that I was 

 altogether mistaken in my interpretation of the larvae which I had 

 found, and that my series belonged in fact to the normal order of 

 development. 



By the courtesy of Dr. Spengel I have been enabled to inspect his 

 magnificent series of preparations, illustrating the whole life-history 

 of Balanoglossus, and so to become convinced of the truth of his 

 statement ; I now, therefore, take the earliest opportunity of with- 

 drawing my previous statement, and desire to express my regret at 

 having placed such an erroneous doctrine on record in the ' Pro- 

 ceedings ' of the Society. 



I beg also to thank Dr. Spengel most sincerely for his kindness to 

 me in this matter, 



