Development 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 larve of Vanessa 
uriice 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 gallica 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 larvee produced from these eggs until 
they are full-grown. From these larvee 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 larve 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 larve, the scarcity of food often causes the 
development and growth of the larve 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 workers (which, 
as larvee, 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 larvee of which are developed in their food a dis- 
proportionate number of females are developed, Landois refers 
* Wahre Parthenogenesis bei Schmetterlingen und Bienen, 1856, p. 92. 
(English translation, p. 74.) 
