224 THE USE OF THE MICROSCOPE 



12. Trivalents in Triploid Tulips. -Bulbs of diploid 

 tulips, such as, Keizerskroon, Massenet, or Pink Beauty, 

 can be examined by cutting open in September or October, 

 or sometimes in November. Besides iron-acetocarmine 

 preparations, fixing with chrom-acetic-formalin, and stain- 

 ing the smears with iron-brazilin, or alcoholic iron-haema- 

 toxylin, show the diaphase well. To be compared with 

 the common diploid tulips. (Newton and Darlington, 

 BeUing.) 



13. Trivalents in Triploid Tomatoes. — Triploid tomatoes 

 occasionally occur. They may be picked out by bearing 

 few fruits and seeds, and may be identified by their pollen. 

 The pollen mother cells can be stained with iron-acetocar- 

 mine; or smears can probably be fixed in chrom-acetic- 

 formalin, and stained with iron-brazilin or iodine 

 gentian-violet, or iron-haematoxylin in 70 per cent alcohol. 

 (Mann, Lesley.) 



14. Trivalents and Quadrivalents in Triploid and Tetra- 

 ploid plants of Datura stramonium. — Tetrsiploid plants and 

 branches occasionally occur. They may be recognized 

 by the larger flowers, pollen grains, and seeds. Triploids 

 may be sometimes produced by pollinating tetraploids 

 from ordinary diploid plants. The pollen mother cells fix 

 and stain excellently in iron-acetocarmine. They can also 

 be fixed in smears by chrom-acetic-formalin, and stained 

 for several hours in iron-brazilin, or iron-haematoxylin in 

 70 per cent alcohol. The cells must be squeezed flat by 

 pressure on the cover. (Belling and Blakeslee.) 



15. Non -reduction. — Examine especially the first and 

 second metaphases of haploid plants (Datura, Nicotiana, 

 etc.). Make new haploids if necessary, by the two methods 

 given above. (Haploids of lihes or hyacinths would be 

 useful if they could be made.) Also expose ordinary 

 diploid Daturas, etc. to cold in an ice chest, and then put in 

 a greenhouse. See if (a) there is always an interphase 

 before the non-reductional division of the full number of 

 chromosomes; or if (b) there is no interphase; or if (c) 

 there is an interphase in some plants and not in others; 



