56 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



by the Juue ?i\jriciiJa, I founil to my surprise that the 

 brown patches on the sand were once more present, and 

 now showed dense swarms of Amphidiniinn , bnt no 

 Diatoms. This condition remained for a few days, and 

 then disappeared, and on the 16th the Nayiculoid 

 Diatoms were back again in force and remained abundant 

 during the ITth and 18th of September. On the last two 

 dates some small and rather greener patches were found 

 which on examination proved to consist of a bright green 

 Euglenoid Infusorian. The Aiuphidlnid made theii 

 appearance next on October 2nd, and remained more or 

 less in evidence during the month. They were in great 

 abundance on the 12th and 13th, again on the 19th, and 

 finally, on the 25th and 2Gth. No Am ph id in in were 

 found between October 28th and November 1st, 

 but on November 2nd some small patches again made 

 their appearance in the usual positions on the beach and 

 then died away. 



The following may be given as a brief tabular 

 statement of these remarkable alternations of the animal 

 {Amphidinitim) and the plant (Diatoms) on the beach at 

 Port Erin during these seven months in 1911. 



April 7 to May 1 ... Amphidinium, and a few Diatoms (Navicula) 



June 3 to July 22 ... Diatoms fsome Xavicula, others Pleurosigma) 



.Sept. 9 and 10 ... Amphidinium in abundance, Diatoms absent 



Sept. IG to 18 ... Diatoms (naviculoid) 



Oct. 2 to 2U Amphidinium in abundance. Diatoms absent 



Oct. 28 to Nov. 1 ... No Amphidinium present 



November 2 ... ... Amphidinium (3 small i)atches) 



Since this date neither organism has boon found. 

 and no brown patches have been seen on the sand. 



Presented in this form the evident alternaiion 

 bclwoon these two kinds of oiganism is very striking, 

 and, altliongli it may be impossible as yet to give any 

 full oxphi nation, still the facts seem to point to tlio 

 probability that tlie cause of the ])lienomenon is a 

 physiological our und tli;it the cxphiiijit ion may consist in 

 showinij- that cafli oi'i'anisin in turn in its nictaholisin 



