A HUNDRED M ICUUSCUl'lCAL OBJECTS 229 



of iyc>, MS well as those with seven pairs. Pollen niollxM- 

 cells are to be pressed out under the cover-glass, from the 

 cut anthers, in iron-acetocarmine. Smears may be made 

 also, fixed in chrom-acetic-formalin, and stained with iron- 

 brazilin, or with iron-hsematoxylin in 70 per cent alcohol. 

 The cells are united in cylinders, and require judicious 

 subsequent pressure with a needle to free them. Investiga- 

 tions on the inheritance of the eight-chromosome form may 

 be made. (Gotoh, Belling.) 



29. Chromomeres of Tradescantia. — Pollen mother cells 

 of T. virginiana at the first metaphase, or earlier, are 

 pressed out into iron-acetocarmine, as in 3. Good iron- 

 brazilin smears can readily be made, but should not be 

 stained too deeply, as may readily happen. In the excel- 

 lent acetocarmine preparations, the cytoplasm and chromo- 

 somes are readily squeezed from the cells. The numbers 

 of compound chromomeres can be counted in each meta- 

 phase or anaphase chromosome. In the iron-brazilin 

 mounts the ultimate chromomeres of leptotene and zygo- 

 tene stages can also be seen. (Sands, Belling, Kuwada.) 



30. Chromosomes of the Three Wheats with Different 

 Numbers. — Pollen mother cells of the three varieties or 

 species of Triticum with 7, 14, and 21 pairs of chromosomes, 

 respectively, are pressed out in iron-acetocarmine, as in 3. 

 Iron-brazilin smears are also made. Investigation may 

 be carried on as to the sizes, shapes, and configurations of 

 the bivalents. The first-generation hybrids of these 

 wheats may also be examined as to the division of univa- 

 lents at the first metaphase, using the tests in 20 and 21. 

 (Kihara, Sax, Thompson, etc.) 



31. Second-metaphase Chromosome Groups in Pollen 

 Mother Cells of Datura, Nicotiana, etc. — Preparation as in 

 3. Cytoplasm and chromosomes pressed from the cell. 

 An investigation might be made on the position of the larg- 

 est and smallest chromosomes in the metaphase plates. 

 (Belling.) 



32. Sperm Nuclei of Flowering Plants. — Soon enough 

 after self- or cross-pollinating, open ovary and fix ovules with 



