Contr. towards the Embryology and Anatomy of Polistes pallipes. 181 



studied we were unable to find cell boundaries, or any indication of 

 cell formation, present within the gonads. 



The nuclei within this youngest gonad would average about 

 0.0045 mm in diameter ; each contains one or two nucleoli, seldom a 

 greater number, which are irregulär in shape, but generally somewhat 

 elongated; they are seldom angular, their surface as a rule being 

 ronnded (Fig. 2). When but a Single nucleolus is present it is apt 

 to be elongated, when two or more are present, they are generally 

 more rounded. Each nucleus also contains a number of chromatin 

 granules; these are much smaller than the nucleoli and they are 

 mostly peripheral in position, a few only, lying at any distance from 

 the nuclear membrane. The achromatin does not form a definite 

 network, but appears as Strands which connect the chromatin granules 

 with each other, and with the nucleolei. Neither in this, nor in any 

 other embryo studied, were dividing nuclei seen. 



The nuclei, found in the embryonal gonads of Polistes^ are very 

 similar to those described and figured by Grünberg (12) for Bomhyx 

 mori, and we judge that botli were of about the same age. As just 

 mentioned, we failed to find any cell boundaries at this stage. 



It was very difficult to stain the nuclei of the gonads in these 

 early stages and we obtained better results by using the commonest 

 stain, such as Mayer's haemalum, than with the more complicated 

 ones used for nuclear structures. With this stain just mentioned, the 

 bodies we have called nucleoli, are not so darkly colored as are the 

 chromatin granules; the same result was obtained by using Hei den- 

 hain's iron-haematoxylin. With Flemming's triple stain no differen- 

 tiation could be obtained; with safranin aloue both nucleoli and 

 chromatin granules stained equally, and the same result was obtained 

 with acid-fuchsin. 



Older embryos were very similar to the young ones; the 

 reproductive organs were somewhat changed, but not the contained 

 nuclei. With the growth of the embryo the nuclei increase somewhat 

 in size, and it is noticeable, that within the gonad, they show a 

 Variation in this respect, some being larger than others. Bessels (1) 

 long ago observed that, in the ovary of Lepidoptera, the cells were 

 at first all the same size but later, grew and differentiated. These 

 larger nuclei have no definite position within the gonad, most of 

 them were centrally situated but some were seen lying close to, or 

 against, the wall. In an embryo 1,5 mm in length, one of these 

 large nuclei measured 0.0075 mm in diameter; the average diameter 



