CHROMOSOME STUDIES 213 



the middle formed by the junction of the proximal knobs of 

 7 and 11. In 5-9 the middle, perpendicular ring is much in- 

 creased in extent at the expense of the horizontal'* portion of 

 no. 9, which is a cross, and of no. 5, the halves of which are 

 merely in contact. But in 8-10 the separation is such that 

 we have three rings. The middle, perpendicular ring ha^ con- 

 strictions (x, x) near the middle of each part, the points of junc- 

 tion between 8 and 10. The plane of the terminal rings is at 

 right angles to that of the middle ring. They may be referred 

 to as horizontal rings. "* Their distal parts have split so as to 

 form crosses, the planes of which are parallel to that of the 

 middle ring. No. 6 clearly has the form of a cross. In all 

 of the autosomes the four longitudinal parts are evident in places. 

 I believe that they have originated from conditions like those 

 shown in figures 164, etc., where each of the eight ordinary 

 chromosomes consists of four longitudinal strands lying close 

 together. 



Still later prophases of the 7-11 and 8-10 chromosomes are 

 shown in figures 175 and 176. In figures 176 and 177 especially 

 the points of junction (x, x) between chromosomes 7 and 11 is 

 very evident on each of the four strands of the middle ring. 

 Here, too, the four longitudinal parts of the chromosome may 

 be very readily made out. An unusual occurrence is illustrated 

 in figure 177. One of the two compound chromosomes in con- 

 jugating has evidently at some time, probably during parasynap- 

 sis, enclosed the other. Here, at the end of the period, they 

 are still in the same relation to each other and neither seems to 

 have been affected by it. 



Figures 178a and 178b are of a late prophase showing all nine 

 chromosomes. The constrictions at x, x indicate the com- 

 pound character of the three largest paiTs, which is also shown, 

 even more distinctly, in the early metaphase of figure 179. 



A careful comparison of this figure (179) of Chorthippus 

 with the corresponding figure (157) in Syrbula is very instruc- 



^ I use the term 'perpendicular ring' to show that this portion of the chromo- 

 some, when the latter takes its position on the spindle at metaphase, will be 

 perpendicular to the plane of the metaphase plate, and 'horizontal ring' to desig- 

 nate the portions parallel with this plane. 



