226 THE USE OF THE MICROSCOPE 



18. Chromosomes Not Conjugating in Species Hybrids of 

 Canna. — Pollen mother cells of the canna Austria (Cloth 

 of Gold), or the canna clone Italia, are pressed from short 

 cut segments of the anthers into iron-acetocarmine, and 

 allowed to stain well before covering gently. (Iron-brazilin 

 smears may be also tried.) The water-immersion objective 

 and yellow-green light are to be used. How many biva- 

 lents are to be seen, and are these united at one or both 

 ends? There are 18 somatic chromosomes. They should 

 be compared with the 9 bivalents of a wild canna, such as 

 C. flaccida of Florida. (Belling.) 



19. Trivalents of Triploid Cannas. — Plants (or cut 

 flower stems) of the true triploid cannas, Gladiator and 

 Firebird (Burpee), and probably Wyoming, are exposed to 

 cold (natural or artificial) for a day or so, and returned to 

 heat. Their pollen mother cells are then to be examined, 

 as in 18. The nine trivalents can be studied to ascertain 

 the proportional numbers of the different configurations. 

 (Belling, Kuwada, Kihara.) 



20. Trivalents, Bivalents, and Univalents of Triplex 

 Cannas. — Preparations are to be made as in 18. The 

 cannas Pennsylvania and Indiana do not have nine triva- 

 lents, but a mixture of trivalents, bivalents, and univalents. 

 They probably came from back-crosses of the first filial 

 plants of a species cross (such as Austria and Italia are 

 stated to be) with pollen from a parental or some allied 

 form, non-reduced egg cells alone being viable. If none of 

 the univalents divide at the first division, the total number 

 of chromosomes at the first anaphase will be 27, as in true 

 triploids. Several others of the orchid-flowered cannas 

 resemble these two. (Belling.) 



21. Trivalents, Bivalents, and Univalents of HemerocaUis 

 fulva. — Good preparations can be obtained with iron- 

 acetocarmine, and also with iron-brazilin. The latter 

 require pressing out. This is apparently a triplex plant, 

 possibly arising from an Fi species hybrid, of which an 

 unreduced egg cell was fertilized by a pollen grain from one 

 of the parents. Absence of division of univalents at the 



