A HUNDRED MICROSCOPICAL OBJECTS 22 



o 



nodes at earliest and latest diaphase can be found (Belling). 

 Iron-brazilin mounts can also be made, but the nodes are 

 not so easily counted in them. 



8. Numbers of Nodes in the Bivalents of Tulipa.— ]\Iake 

 iron-acetocarmine preparations from the pollen mother cells 

 of ordinary diploid tulips, the bulbs being cut open in 

 October. Or make smears, fix in chrom-acetic-formalin, 

 and stain in iron-brazilin for 2 or 3 hours, or in alcoholic 

 iron-haematoxylin. jVlount in immersion oil under covers 

 0.17 millimeter thick. Press out cells in early, middle, and 

 late diaphase. Count nodes in all twelve bivalents. 

 (Newton, Belling.) 



9. Effects of Changes of Temperature on the Reduction 

 Division in Hyacinthus. — Yellow Hammer is an easily 

 identified diploid variety of Hyacinthus orientalis. In 

 October, or early November, when the pollen mother cells 

 are (a) at the leptotene or pachytene stage, or (6) at the 

 first metaphase, alternate the bulbs between the ice chest 

 and the hothouse. Mount the first metaphase, or the 

 young pollen grains, in iron-acetocarmine. Look for cases 

 of non-conjunction, non-disjunction, non-reduction, and 

 non-division. Also for cases of fracture at the constriction, 

 and for union of two chromosomes. (Belling, Michaelis, 

 Sakamura and Stow, de Mol, Shimotomai.) 



10. Effects of Changes of Temperature on the Matura- 

 tion Divisions in Uvularia. — Treat plants of Uvularia 

 grandiflora or U. perfoliata as in 9 with heat and cold. 

 Mount specimens in acetocarmine, and also fix smears in 

 chrom-acetic-formalin. Investigation as in 9 (Belling). 



11. Trivalents in Triploid Hyacinths. — Bulbs of true 

 triploid hyacinths, such as. King of the Blues, Lady Derby, 

 Queen of the Pinks, or Grand Mattre, are put over water (or 

 cut open dry). The maturation divisions take place in 

 October or November. Iron-acetocarmine preparations 

 are to be compared with similar preparations of the dip- 

 loid hyacinth (Yellow Hammer, for example). The late 

 diaphase or early metaphase is the best for study, and a 

 water-immersion objective should be used (Belling). 



