Miscellaneous. 299 



overwhelmed with work, can only furnish her young with a scanty 

 supply of nourishment. These small individuals have hitherto been 

 regarded as workers or neuters ; but this denomination is erroneous. 

 Von Siebold 'has dissected many of these small individuals of PoVistes, 

 and ascertained, by the examination of their generative apparatus, 

 that they are not, like the worker bees, females arrested in their 

 development, but perfectly developed females the turgid ovaries of 

 which are filled with eggs ready to be laid. 



As soon as the origiual mothers have thus produced assistants in 

 the form of these active virgins, the increase of the nest takes place 

 rapidly, and the larvae, receiving more abundant nourishment, are 

 transformed into wasps as large as their mother. Towards the end 

 of June or the beginning of July the comb presents a large surface 

 and is composed of a very great number of cells. At this period 

 some male individuals may be remarked for the first time among the 

 numerous large and small females. Their number soon increases 

 considerably. The observation of these facts suggested to Yon Siebold 

 that there might exist, in Polistes, a division of physiological labour — 

 in this sense, that the feciindated females of the preceding year pro- 

 duce only female eggs, whilst the virgins of the new generation 

 produce male eggs parthenogene tic ally. This hypothesis seemed to 

 find support in the small number of ovarian tubes in Polistes, which 

 can only produce an inconsiderable number of eggs. 



Experiment has confirmed this hypothesis in the most striking 

 manner. Yon Siebold selected a certain number of nests in the spring, 

 at a period when the mothers had already reared one or two assistants. 

 He removed from these nests the mothers, and dissected them in 

 order to ascertain the condition of their generative organs. He 

 always found the ovarian tubes in full activity, and the seminal re- 

 ceptacle full of mobile spermatozoids. At the same time he entirely 

 emptied all the cells of these nests which contained eggs or any 

 small larvse, preserving only the larvae of large size. Notwithstand- 

 ing the disappearance of the mothers, the little virgins continued to 

 take care of the larvae which had been preserved, and consequently 

 the colonies did not perish. Yon Siebold took the precaution to 

 mark, in each of the nests experimented upon, the occupied and 

 empty cells. In a few days he perceived that some of the latter 

 contained eggs. Careful examination even enabled him to surprise 

 some of the little virgin wasps at the moment when they were 

 ovipositing at the bottom of a cell. These individuals were at once 

 sacrificed, when the six ovarian tubes were found to be completely 

 developed, filled with ova in different stages of growth, whilst the 

 seminal receptacle was perfectly formed but completely empty. 



During this time, thanks to the assiduous care of the young virgins, 

 new female individuals, produced from the large larvae which had 

 not been sacrificed, arrived at their complete development, and at once 

 took part in the labours of the society. The nests were consequently 

 enlarged by new cells, which were speedily occupied by eggs laid by 

 the virgins. All these eggs (and this is the important fact) were 

 devfloped notwithstanding the absence of fecimdarion, and gave 



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