1922] Possible Pedogenesis in the Blow-fly 129 



December, 1919, 502 eggs were hatched in this way and in no 

 instance did an egg produce more than a single larva. It was 

 therefore concluded that Calliphora gave no evidence of poly- 

 embryony such as has been found so abundantly in certain 

 hymenopters. 



To test again the possible production of maggots from other 

 maggots, the experimental procedure of April 2, 1919, was 

 repeated. On October 2, fifty jars were set up with fish-meat. 

 They were examined on October 28 and were found to contain 

 no maggots. On the next day into each of twenty-five of these 

 jars a single newly hatched maggot was introduced and the 

 remaining twenty-five were kept as checks. On November 10 

 an examination of the jars showed no maggots in the twenty-five 

 check jars, no maggots in three of the infected jars, probably 

 because of accidental death, one maggot each in twenty of the 

 infected jars, eight in one infected jar, and twenty-one in another. 

 The maggots in the last two jars were carried on to pupation 

 and hatched. All proved to be Calliphora erythrocephala. Of 

 the eight in- the first jar, five were males and three were females. 

 Of the twenty-one in the second jar, five failed to hatch, nine 

 emerged as males and seven as females. 



On October 18, a second set of fifty jars was started in the 

 same way as in the preceding test. On November 15 these jars 

 were examined and found to contain no maggots showing that 

 they had not been accidentally infected. Into each of twenty- 

 five of them a single newly hatched maggot was introduced and 

 the jar closed. On November 26 pupation was completed and 

 an examination of the set showed that the twenty-five check 

 jars were without pupae as well as six of the infected jars; eighteen 

 of the infected jars contained each a pupa, and one contained 

 seven. These seven were subsequently hatched and all proved 

 to be Calliphora erythrocephala, four females and three males. 



The tests of October 2 and October 18 were carried out 

 with such precautions that it seems impossible that the i-esults 

 could be due to accident. The increases observed have alwaj^s 

 occured in the autumn and never in the spring and I am, there- 

 fore, led to believe that in October and November or even later 



