S. A. Arendsen Hein 249 



which 254 eggs were obtained. The table on page 248 supplies a survey 

 of the number of eggs deposited by each group of beetles, together with 

 the dates on which they were laid. All the eggs gathered were put in 

 the incubator; nqne of them were developed ; after some time all were 

 shrivelled. 



It cannot be concluded from this experiment whether oviposition 

 (without previous mating) is proper to many beetles or to a few indi- 

 viduals only. The 56 eggs produced by group No. 1 may originate 

 from one as well as from all the 24 beetles. But then the experiment 

 had not been made in view of an answer to this problem. I wished only 

 to know whether non-fertilized eggs can be hatched parthenogenetically. 

 We may safely conclude, from the result obtained, that, when left to 

 themselves, without the application of artificial means, they do not 

 develop as a rule. I shall refer to the problem of artificial partheno- 

 genesis in due course when the experiments made in this line have come 

 to an end. 



6. Development of the Adult Coloration. 



Not all the organs of the beetle complete their coloration simulta- 

 neously. In which organs the pigment shows itself first may best be 

 observed in the pupa. The mandibles and the eyes differentiate first 

 from the surrounding parts and are already very dark when the antennae 

 and the legs display only the beginning of a brown colouring. Shortly 

 before the casting of the pupal moult the condition of the pupa is as 

 follows : 



black. 



reddish brown. 



Eyes 



Mandibles ... 



Head 



Antennae ... 



Tibia and tarsus of the 6 legs 



Distal edge of the last abdominal segment j 



Prothorax ... ... ... ... ... light orange yellow. 



The rest of the pupal body is still uncoloured, not to mention those 

 parts that are removed with the pupal skin and no more present or con- 

 spicuous in the beetle, such as the spines on the last segment and the 

 spines on the lateral edges of the abdominal segments. In the beetle 

 just emerging from the pupal skin the light orange*lfed prothorax and 

 the deep black eyes contrast strongly with the white of the elytra. An 

 examination of the organs in this stage will show the following facts : 



