296 KANSAS UNIVERSITY SCIENCE BULLETIN. 



ZOOLOGICAL LABORATORY. 



their unusually large size, and especially on account of the 

 great variation in size among the members of the complex. 

 The tables which have been arranged in plates XXI and XXII 

 were gotten up from such complexes as are represented by 

 figures 30-33, 40, 41 and 1-6. In these tables the twelve chro- 

 mosomes of a cell are strung out in a horizontal row or series. 

 Each individual chromosome is given a position in its series 

 according to its size, the largest, No. 12, coming first. No. 11 

 second, etc. The series are placed one below the other, so that 

 like chromosomes will appear in the same column. In this 

 way all the No. 12's throughout the series of cells will be 

 found in the first column, the No. ll's in the next, and so on 

 for all the chromosomes belonging to each specific size or rank. 

 In the plates the first twenty-five series are from that many 

 polar views of first spermatocyte metaphases and were taken 

 from four different animals (A, B, C, D). In series 24 and 

 25, under D, the chromosomes seem much larger than in any 

 of those preceding. This was due to the stain used, Flem- 

 ming's tricolor, which has a tendency to swell the structures. 

 The chromosomes of the other series were stained with iron- 

 hsematoxylin. In series 26-29 are shown the chromosomes of 

 the two forms of second spermatocytes, those with the ac- 

 cessory and those without, and in 30 and 31 two series from 

 spermatogonial metaphases (taken from figs. 2 and 6, plate 

 XVIII). 



In arranging the members of a series it was often difficult 

 to determine the relative position of some of those nearest in 

 size, because in some cases there was very little size variation 

 while in others the true size was hidden on account of the 

 position of the chromosome in the cell-plate. The latter was 

 the case when ring-like forms were turned on edge or when 

 those of a rod or kidney shape were viewed from the end. But 

 although there may be doubt in regard to the position and size 

 of those nearest each other in the series, such as Nos. 6 and 7 

 or 8 and 9, there is absolutely no danger of confusing those 

 of such wide range as Nos. 12 and 6, or 10 and 5, or even of 

 those as near as Nos. 10 and 7. 



There are in a general way six columns (12, 11, 10, 9, 7, 

 and 4) in which ring-like forms occur. The other columns con- 

 tain chiefly straight or bent rods. In regard to the ring-like 

 forms a word of explanation is here necessary. A ring, as has 



