192 The Ohio Naturalist. [Vol. XIV, No. 1, 



Gates (4) in his paper on Oenothera riibrinervis states that 

 the spirem constricts into fourteen chromosomes which break 

 apart in pairs and then form the bivalent chromosomes by a 

 folding together and fusion of the parts of each pair. Davis 

 says there are ring-shaped chroinosomcs, some of which are 

 linlced together in O. grandiflora (1). He says these are present 

 as soon as the sporocyte passes out of the synizetic stage. In 

 O. biennis (2) he finds a chain of fourteen chromosomes breaking 

 into seven pair's from which seven chromosomes are formed by 

 fusion. This method of chromosome foraiation of course is 

 essentially the same as that of loop formation, but I have found 

 the loops definitely formed and just as definitely contracting 

 until there are seven chromosomes formed from the seven loops. 

 These results are the same as were found in Fuchsia (S). The 

 loops frequently form quite definite rings as is seen in figure 16. 



In figure 19, the chromosomes still show something of their 

 ring and loop character and there are two nucleoli shown. The 

 next figure (Fig. 20) shows a certain amount of loose material in 

 the nucleus which may be derived from the nucleolus although 

 there is no direct evidence for this conclusion. The next two 

 figtires (Figs. 21 and 22) show the chromosomes broken apart and 

 the cytoplasm flowing into the nuclear space. The nuclear wall 

 has entirely disappeared. In the cytoplasm are seen great num- 

 bers of prominent granules. These remain in the cytoplasm 

 throughout the reduction process. Whether these are starch or 

 not was not definitely determined. Figure 23 shows the beginning 

 of the formation of the spindle with the chromosomes being 

 drawn into the equitorial plane. Figure 24 is the mother star 

 stage at the time when the chromosomes begin to be segregated 

 into the univalents. The next two figures (Figs. 25 and 26) do 

 not show the full quota of chromosomes but show the beginning 

 of the true reduction in those that can be seen. The next two 

 drawings (Figs. 27 and 28) represent nietakinesis stages with the 

 chromosomes half way to the poles. Figures 29 and -30 are 

 daughter star stages. The lower pole of figure 30 shows a slight 

 beginning of the nuclear wall. The seven univalent chromosomes 

 arc about half the size of those appearing on the mother star. The 

 number can be easily counted at this stage. 



Following this stage the nuclear membrane develops rapidly 

 and the daughter nuclei swell to a much larger size. The chromo- 

 somes remain as distinct bodies although there is some distribu- 

 tion of the chromatin material (Fig. 31). Even in the resting 

 condition the chromosomes in the two daughter nuclei remain as 

 seven distinct bodies and there is no real reticulum developed 

 (Fig. 32). At this stage all traces of the spindle have disappeared. 



Soon after, the second division begins (Fig. 33) and the chro- 

 mosomes in the mother star are again distincth* visible as small 



