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THE AMEBIC AX NATURALIST [Vol. XLIV 



Although I have kept large numbers of Hyrlro'uh-x literally bursting 

 with <ron it al products under observation, I have seen natural oviposition 

 only twice. 



Professor A. L. Treadwell has also stated that he has observed 

 a similar operation in the egg-laying of Dopatra. He says 

 further : 



Whether the epidemic of egg-laying, in which when one starts the 

 others follow, is due to a similar stimulus acting on all of them at once, 

 or whether the first one stimulates the others, is not certain. I should 

 consider the latter the more probable explanation. I found that to be 



So far as could be ascertained under casual observation the 

 individuals participating in the performance were about equally 

 males and females, a further indication of the essentially normal 

 character of the phenomenon. It would seem as if specimens of 

 approximally similar age and condition of maturity ripen the 

 genital products at a given time, and under the appropriate 

 stimulus discharge them simultaneously. 



The behavior will recall the somewhat similar exhibition of the 

 pololo worm, whose swarming and coincident spawning has been 

 described by several observers. .May we not conclude that these 

 several phenomena are but varying expressions of a spawning 

 habit more or less common in annelids, and indeed not unknown 

 among other of the lower invertebrates, though differing of 

 course in various details? 



It may be mentioned in conclusion that the ova discharged by 

 the worms at the time described were promptly fertilized and 

 developed in a perfectly normal and regular fashion. 



