STOUT AND 8V8A, CHROMOSOME IRREGULARITIES 17 



in our PL II, Fig. 17. Juel's Fig. 14 is of one of the two plates of the 

 second division and this one indicates 18 X-shaped or double chromo- 

 somes, quite as in one of the groups in our PI. II, Fig. 25. Juel says in 

 the explanation of this figure that the number of chromosomes is at least 

 18. 



The normal number of 6 bivalents or of bivalents and univalents to the 

 total of 12 univalents seems to be approximated in various of the figures 

 drawn by Strasburger and by Juel, but in other of their figures numbers 

 higher than the normal are to be noted, quite as they are found in our 

 material. 



Recently Belling (1925) published a drawing (his Fig. 10) of the 

 metaphase of the first division with 11 chromatin masses, many of which 

 are split and all of which are evidently in stages of fragmentation. He 

 also shows in a late anaphase of a first division or possibly in the pro- 

 phase of the second division, two groups of 18 and 15 split or X-shaped 

 chromosomes quite similar to the cases which we show in PI. II, Fig. 25. 

 Belling concludes that a plant of H. fulva is a triploid with 33 chromo- 

 somes in the somatic cells, but he notes that it must be an irregular trip- 

 loid with varying numbers of trivalents, bivalents and univalents in the 

 first metaphase. His study did not involve examination of the somatic 

 cells. 



Tischler (1927) records the haploid number of chromosomes for plants 

 of H. fulva as 16 and cites as the authority a not yet published manu- 

 script from S. Xawaschin. 



Schiirhoff (1926, p. 461) reviews various of these conflicting state- 

 ments regarding the chromosome number in //. fulva and concludes 

 with the statement "Ich priifte daher die Chromosomenzahl nach und 

 fand 24 als haploide Chromosomenzahl/' 



Timm (1928) reports that the haploid number of chromosomes in 

 pollen mother cells of certain plants of H. fulva is 12 and he shows (his 

 Abb. 2) an equatorial plate of the first reduction division with 12 chro- 

 matin masses, which he considers to be bivalents. He does not report 

 studies of the somatic cells of H. fulva, but he states that cells in the 

 root tips of II. citrina possess 24 chromosomes. This we do not confirm. 

 Four different strains of //. citrina are being grown at The New York 

 Botanical Garden. Sections of the root tips of two of these strains have 

 been studied and in all cases the sections show 12 chromosomes. Since 

 the publication of the paper by Timm the prepared slides of these root 

 tips were carefully re-examined * and the count of 12 fully verified. 



* This study was made by Miss Clyde Chandler, technical assistant of The 

 New York Botanical Garden. 



