CHROMOSOME STUDIES 239 



split condition pass to the poles as usual. I believe the Schrein- 

 ers, like most of the workers on Amphibia, have frequently 

 shown incorrectly in Tomopteris these compound chromosomes, 

 owing to a misunderstanding of the conditions. The common 

 error is to represent the loops at the junction between the per- 

 pendicular (middle) and horizontal (terminal) rings as though 

 they simply crossed ('06a, figs. 34-38), whereas they spht and 

 then contribute to each side of the horizontal ring in the manner 

 I have shown for chromosome 7-11 in figures 173a, 174, and 176. 

 In the early stage 'h' it is not so easy to see the nature of these 

 junctions, but in the 'i,' 'j,' and 'k/ stages the figures of most 

 authors show very clearly that these crossings have been mis- 

 interpreted; e.g., Janssens ('05, figs. 58-60) in Batrachoseps, 

 ('01, figs. 8, 9) in Triton; Flemming ('87, figs. 3, 4, 7a, 8) and 

 Meves ('96, fig. 50) in Salamandra; Gregoire ('99, figs. 7, 8) in 

 the lily; Atkinson ('99, figs. 1, 2, 3, 4) in Trillium. In the paper 

 by Agar ('11) on Lepidosiren figure 15 shows this stage, though 

 not very clearly. 



In Copepoda the chromosomes are so short that one could 

 not expect to find two- and three-ring structures in the prophases 

 and metaphases of the first maturation, such as are found in 

 species with long Vs. But short V's and the transverse seg- 

 mentation are found, as in Chorthippus. This point of seg- 

 mentation corresponds, I believe, to the apices of the V's of 

 Chorthippus, even though the chromosome may be a rod. The 

 resemblance to my stage H' may be seen in the prophase figures 

 of Lerat ('05, figs. 18, 19, 39). In his figures 27-30 and 40, 

 (early anaphases of the first maturation) the V nature of many 

 of these chromosomes is evident in the longitudinal split of their 

 arms. In the first maturation prophases of Matscheck ('10, 

 figs. 37, 62-64, 75, 78) the paired bivalents may be considered 

 to correspond with those of my figures (163-168) of stage 'h.' 

 In slightly later stages ('i,' 'j') the transverse segmentations on 

 both rods of each bivalent are similar, I believe, to the constric- 

 tions on each of the two strands of my compound bivalents 

 (figs. 168, 176). These paired chromosomes, each transversely 

 segmented and longitudinally split, give rise to four similar 



