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Wm. S. Marshall, 



ovary proper and oviduct not present, but the gonads do not show 

 any trace of the tubules which later appear in the young larva. 

 After the appearance of cells in the gonads of the young larvae, 

 some of them begin to increase considerably in size; the presence 

 of these large cells distinguishes the ovaries from the testes. At 

 first each of the three ovarian tubules, connected at their base, is 

 similar throughout its entire length, and, it is only in the older larvae, 

 that we can distinguish the different parts. 



When either embryos or larvae vrere of nearly the same size it 

 V7as very difficult to determine their relative ages. In many cases 

 we have used the length of embryo or larva, but canuot say that 

 this means very much. The eggs of Polistes show a difference in 

 size, and the length of embryos of the longer eggs would, at an 

 eqaal age, be greater than there of the shorter ones. Amount of 

 contraction by different preserving fluids might also make some 

 difference. In many pupa, the ends of the tubules were twisted and 

 bent, so that it often became difficult to give their exact length. 

 The length of the tubule cannot always be used as a Standard of 

 relative age, some of equal lengths showing a difference in the 

 development of the enclosed cells. 



Embryo. The youngest embryo studied, the one with which 

 we begin our account, was 1.35 mm in length; its gonads were each 

 0.04 mm wide and a little over twice as loug. Each gonad is fiUed 

 with protoplasm which shows a great similarity at all points, in some 

 there are a few small vacuoles present, but the majority, did not 

 contain them. Nuclei of the same structure are found throughout the 

 entire gonad; in it they have no definite position and fail to show 

 a regulär epithelial arrangement; they do not lie at any regulär 

 distance from each other, some nearly touch adjacent nuclei, and 

 others are a little distance apart. In Chalicodo7na Carriere and 

 Burger (6) found that the young gonads contained a number of 

 similar cells. A comparison of this embryo, with others which were 

 a little longer, shows no difference in the size or arrangement of 

 the contained nuclei, which have either a round or an oval form, and 

 Vary but little in size (Fig. 1). A few of the nuclei are irregulär in 

 shape, but an examination of all the sections shows that the round 

 form predominates. We find here in Polistes^ as has been described 

 for a number of animals, that the reproductive organ in the youngest 

 stage or stages, is a syncytium; in the different embryos which we 



