Demlo])ment of the Sexes in Insects. 211 



Dzierzon himself doubted his own theory, because, in the 

 experiments on intercrossing German and Italian bees, re- 

 markable and inexplicable phenomena occurred which could 

 not be brought into harmony with Dzierzon's theory, I must 

 appeal to the arguments which I have already urged against 

 this doubt of Dzierzon's*. 



Landois states that by taking very young larvae of Vanessa 

 urticoB and feeding them imperfectly he reared from them only 

 males, and by feeding them abundantly only females. This 

 assertion is in complete contradiction to the phenomenon which 

 may be observed in Polistes galUca with regard to the produc- 

 tion of the sexes. Every female of Polistes fecundated in the 

 autumn, after passing through its winter-sleep, founds a separate 

 colony at the commencement of the spring ; it makes a comb for 

 itself, furnishes the cells of this with eggs, and then, still 

 quite alone, feeds the larvae produced from these eggs until 

 they are full-grown. From these larvag the so-called workers 

 (that is to say, small female individuals) are always developed ; 

 male individuals are never bred in the months of June and July ; 

 and it is only in August that the first males issue from the 

 operculated cells of these colonies of Polistes. According to 

 Landois's theory, the larvae reared by the solitary Polistes 

 mother ought to furnish males, as this brood is usually very 

 scantily provided with nourishment, and indeed often left for 

 a considerable time without food by their mother, which has 

 to complete the business of feeding them without any assist- 

 ance. This starvation of the brood of Polistes occurs when the 

 temperature becomes cold, when the sky is overcast, and 

 during rain and wind ; for when the weather is unfavourable, 

 even if this lasts for several days, the females of Polistes re- 

 main uninterruptedly inactive, concealed behind their combs. 

 As no supply of food is laid up in the combs of Polistes^ but 

 the nourishment is always poured from mouth to mouth by 

 the Wasp into the larvae, the scarcity of food often causes the 

 development and growth of the larv« to go on very slowly 

 and with interruptions. According to Landois, all these cir- 

 cumstances ought especially to favour the development of 

 male individuals ; but until a large number of w^orkers (which, 

 as larvse, certainly do not revel in a superabundance of food) 

 have been excluded to assist the mother, no male individuals 

 of Polistes are developed. 



In order to give more currency to the assertion that in those 

 insects the larvse of which are developed in their food a dis- 

 proportionate number of females are developed, Landois refers 



* Wahre Parthenogenesis bei Schmetterlingen imd Bienen, 1856, p. 92. 

 (English translation, p. 74.) 



