2 34 BOTANICAL GAZETTE [September 



theory is to be regarded as firmly established on fact. However, it deserves 



investigation, — J. J. Wolfe. 



. The mitoses in the megaspore mother cell of several" liliaceous 

 forms, especially Galtonia candicanSy Scilla sibirica, and Ttilipa Gesnertanar 

 are described in great detail in a paper by Schniewind-Thies.® In Galtonia 

 the mother cell usually gives rise to a row of four potential megaspores, but 

 occasionally only two cells appear in the row, one of which may germinate 

 directly to form the embryo sac, a transition between the condition in Lilium, 

 where the megaspore mother cell develops directly into the embryo sac, and 

 the condition where one of four megaspores produces the sac. In any case^ 

 the first mitosis m the megaspore mother cell shows the reduced number of 

 chromosomes. The second division in a form like Lilium corresponds in all 

 essential details with the second division in a form which is to have two or 



four megaspores, and there is a similar correspondence in the third divisions. 

 In Scilla it is interesting to note that while the number of chromosomes m 

 the gametophyte is eight, the number in the sporophyte varies from eight to 

 sixteen. In Tulipa, at the first mitosis in the mother cell, each of the 

 daughter nuclei contains twelve chromosomes, and in the two succeedmg 

 mitoses this number is maintained at the micropylar end of the sac ; but at the 

 chalazal end the sporophyte number may appear at the second division, or the 

 number may vary, fifteen, sixteen, and twenty-one having been counted. The 

 writer believes that the new generation begins with the reduction division, 

 both in the embryo sac mother cell and in the pollen mother cell, and he has 

 no doubt that the processes in the ovule and in the microsporangium of angio- 

 sperms are homologous. The four potential megaspores correspond to the four 

 microspores (pollen grains); cases of two potential megaspores show a step 

 toward the further reduction which is found in forms like Lilium. The fact 

 that the megaspores take the form of a row is due to position, there being 

 opportunity for early isolation and rounding off as in microsporangia 



Charles J. Chamberlain. 



no 



NOTES FOR STUDENTS- 



MakovL The 



embryo develops continuously, the hypocotyl passing out through the 

 micropyle while the seed is still attached. The phenomenon is said to be 

 well known in Japan, but does not seem to have been recorded in English. 

 J. M. C. 



«Die Reduction der Chromosomenzahl und die ihr folgenden Kerntheilungen 



m 



den Embryosackmutterzellen der Angiospennen. 8vo. pp. 34. pls^s* Jena: Gustav 

 Fischer. 1901. 



9Rhodora2: I13-117. /^j. j. 1902. 





