pinney: chromosomes of anasa tristis. 361 



number of drawings of the accessory taken from cells in the 

 same stage as figure 1. Figure 2 shows a nucleus of the stage 

 immediately following synizesis. The perpendicular column, 

 2a, below figure 2 shows a number of drawings of the accessory 

 taken from nuclei in the same stage as figure 2. The perpen- 

 dicular column, 2b, beneath figure 2 shows a number of draw- 

 ings of the plasmasome taken from cells in the same stage as 

 that shown in figure 2. In the same way columns 3a and 36, 

 4a and 46, etc., are drawings of the accessory and plasmasome 

 from nuclei such as are shown in figures 3, 4, etc., respectively. 

 The horizontal columns A, B, C and D indicate the different in- 

 dividuals from which the drawings were made. The differ- 

 ences in size which are shown in these monoplane drawings 

 depend upon the point of view of the observer. That the ac- 

 cessory is constant in size is easily determined by different 

 focusings. From these drawings there is also found to be a 

 regularity in the relation between the size of the plasmasome 

 and the condition of the active chromatin of the nucleus. From 

 the foregoing observations it is now clear that the thirteen 

 nuclear structures present in the late spermatocyte prophase 

 comprise one accessory, one diminished plasmasome, two small 

 chromosomal elements of opposite parental origin, and nine 

 ordinary tetrads. 



Figures 1 to 10, inclusive, plate LXVIII, show typical polar 

 views of the first spermatocyte metaphase. All of the groups 

 shown are from different individuals, with the exception of 

 figures 2, 3, 4, plate LXVIII, which were in the same section of 

 the same cyst. As many as six of these views, all typical, have 

 been observed in one section in one cyst. There are eleven 

 chromosomes present, each of which, with the exception of the 

 accessory, is composed of four chromatids. The plasmasome 

 has disappeared, also the nuclear membrane. The chromo- 

 somes lie in a clear area surrounded by the cytoplasm. Nine 

 of the complex, including the largest, form a rather compact 

 ring, in the center of which appears the smallest member of 

 the group. The relative positions of the chromosomes forming 

 the ring vary. One chromosome lies outside of the ring. Fig- 

 ure 11, plate LXVIII, shows six of these outer chromosomes at 

 this stage taken from the same individual from which figure 6 

 was made. So, also, figures 12, 13, 14 and 15 are drawings of 

 the similarly located chromosome found in the individuals from 

 which figures 7, 8, 9 and 10, respectively, were made. This 



