ALLEN— SEX INHERITANCE IN SPH^ROCARPOS. 301 



rial was fixed and studied in Professor Mangin's laboratory. The 

 amount available was too small and the stage of development for 

 the most part too advanced to furnish definite results ; but it gave 

 an opportunity for acquiring a familiarity with the plants and for 

 testing methods of fixation. When greenhouse cultures of 5". Don- 



<s^ 



14 



Figs. 12 and 13. Chromosome groups from female gametophytes of 

 Spharocarpos Donncllii: Fig. 12, from a basal cell of an archegone ; Fig. 13, 

 from the basal part of a young archegonial involucre ; x, the large chromo- 

 some. Figs. 14 and 15. Chromosome groups from male gametophytes of 

 S. Donnellii: Fig. 14, from the wall of a young antherid; Fig. 15, from a 

 projecting superficial cell of the apical meristem, possibly an antheridial 

 initial; y, the small chromosome. X 3800. 



nellii were later obtained in vigorous condition, the cytological study 

 was renewed. Some of the results of this study have already been 

 briefly reported (Allen, 1917&). 



Figs. 12 and 13 show typical chromosome groups from cells of 

 the female gametophyte ; Figs. 14 and 15, corresponding groups 

 from cells of the male gametophyte. In each case, as the figures 

 show, eight chromosomes are present. In the female, one of the 

 eight chromosomes {x, Figs. 12, 13) is much longer and thicker than 

 any of the others. The other seven differ in length among them- 

 selves. It is probable that all the individual chromosomes of differ- 

 ent cells can be identified by their length;. but since in sections the 

 chromosomes lie at various angles and thus some of them are always 

 foreshortened in the camera lucida drawings, it will require the 

 assembling and study of a considerable number of figures showing 



