450 Haploids and Autopolyploids 



it bloomed later than the others, it was sterile, and it had small, 

 thick, wrinkled leaves (Fig. 129). 



A similar diploid-tetraploid relationship was observed by 

 Bamford and Winkler when a tetraploid snapdragon that arose 

 spontaneously was found to have larger stems, inflorescences, 

 leaves, and flowers and larger pollen grains and stomata than 

 the related diploid strains. H. J. Sax pointed out that although 

 the frequency of stomata could not be used as an absolute index 

 of polyploidy, there is enough correlation between stomatal fre- 

 quency and chromosome number to make a study of stomatal 

 frequency helpful in a preliminary search for polyploidy in stud- 

 ies of herbarium material. Blakeslee and Warmke use several 

 criteria in making a preliminary separation of tetraploids and 

 diploids. They suggest that although the final decision in regard 

 to any given plant must be determined by counting its chromo- 

 somes, a preliminary, tentative classification may be made from 

 the fact that the tetraploid usually has larger pollen grains, 

 larger seeds, larger stomata, wider, thicker leaves, leaves deeper 

 green in color, larger floral parts, and shorter, stouter fruit. Re- 

 garding the size of stomata, Birdsall and Neatby found that an 

 increase in the number of chromosomes was correlated with an 

 increase in the size of the stomata and a decrease in their num- 

 ber in species of Triticum. None of these criteria is infallible, 

 however, for in some plants the size relationship in the polyploid 

 series does not exist. 



Fankhauser has pointed out that differences in size between 

 polyploids and diploids are found in some animals but not in 

 others. For example, triploid forms of Trichoniscus eUsabethae 

 and of Drosophila as well as tetraploids of Artemia salina and 

 Solenobia have been found that are larger than diploids, but 

 other investigators have reported no increase in size in triploid 

 Drosophila, triploid Habrobracon, and triploid and tetraploid 

 Bombyx. Fankhauser found four triploid specimens of the newt, 

 Triturus viridescens, and only one was strikingly larger than the 

 diploids. The three animals of approximately normal size had 

 body organs which were normal in size but were composed of 

 cells that were larger than cells of the diploids. This discrepancy 

 is explained by the smaller number of cells in these organs. The 

 cells of the triploid are larger than the cells of the diploids, but 

 during development an adjustment is made to this condition so 



