Forms Having an Extra Chromosome. 29 



may be supplemented and confirmed by studies of the germ-cells. 

 For, while her counts are probably correct, yet the phenomena of 

 fragmentation of chromosomes in somatic cells make it highly 

 desirable that they should all be checked by observations on the 

 chromosomes during meiosis. She has determined the chromosome 

 number in 234 plants, including sixteen different mutant types, 11 

 of which types had 15 chromosomes, three had 16, and two were 

 triploid. That (E. mut. albida has 15 chromosomes has been 

 verified by counting the number in thirteen more plants. As will 

 be seen from Table I, she finds an extra chromosome also in a new 

 mutant called bipartite in subovata, elliptica (?) and " type 2806," all 

 from lamarckiana. In addition, a second dwarf type, unlike 

 nanella lata, is found, lata as well as lata X lamarckiana give "type 

 4499" with 15 chromosomes, while lata self-pollinated produces 

 exilis, exundans and " type 5365." None of these latter forms are 

 described, so it is impossible to judge of their claims to separate 

 status, but it seems clear that the three forms appearing in the 

 offspring of lata selfed are secondary in origin, i.e., bear some 

 special relation to lata. All that can be said about these forms 

 at present is that there appear to be at least seven distinct types 

 which might arise through duplication of different chromosomes, 

 and that in addition a number of these types appear to be more 

 closely related to lata. This is certainly the case with semilata 

 Gates, and probably to a different degree or in a different way 

 with several others. This may be connected with other differential 

 factors, but it is useless to speculate about the matter until the 

 facts themselves are clearer. Mut. oblonga apparently has some 

 forms with 15 chromosomes and some with 14. The same is true 

 of rubrinervis. In this case the true rubrinervis of de Vries, a 

 rather weak form, has 14 chromosomes plus a small one. The form 

 which other investigators have called rubrinervis, derived from seeds 

 of de Vries, is taller and more robust and certainly has 14 chromo- 

 somes. It is the form of my early cytological studies (Gates 1908), 

 the form from which rubricalyx originated (Gates 1911), and may be 

 called rubrinervis Gates for identification. It is more like the 

 subrobusta of de Vries, which is derived from rubrinervis X 

 lamarckiana, and may perhaps be identical with that form or with 

 the closely related erythrina (de Vries, 1919) to be discussed later. 

 Miss Lutz concludes that a very large percentage of the mutant 

 offspring of (E. lamarckiana have 15 chromosomes, there being both 

 a larger number of distinct types and a higher percentage of mutant 

 individuals with the extra chromosome. One would feel safer 



