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BOTANICAL GAZETTE 



Chromosomes of Vicia .— Sakamura 22 has found in the nuclei of the root 

 tip of Vicia Faba during metaphase 1 2 already split chromosomes, 2 of which 

 are considerably larger (" M-Chromosomen ") and constantly showing middle 

 and end constrictions ("m und e-Einschniirung ") . In heterotypic mitosis 

 these same constrictions are present in the one large bivalent (" M-Geminus ") , 

 which is believed to be composed of the two M-chromosomes. The fibers are 

 attached at the end of the short chromosomes; but to the M-chromosomes and 

 M-bivalent they are fastened at the middle, causing them to assume a v-shape 

 when traveling to the poles. As a result, there are evident 14 arms in somatic 

 anaphase, this feature probably being the cause of the 14-chromosome count ; 

 while in heterotypic mitosis, due to the splitting of each of the daughter chromo- 

 somes, there are 5 v's and one double V. The chief theory accounting for 

 the origin of the " Einschnurung " is that the M-chromosomes at first are with- 

 out constrictions, and then under certain conditions constrictions arise. This 

 mechanism is shown to be due to an uneven separation of the chromosomes 

 and to the strain of the fibers above this point, causing a stretching of the 

 chromatin, so that when they do dissociate completely there is this apparent 

 constriction. Before the m and e-constrictions could become hereditary char- 

 acters they must first have occurred in heterotypic anaphase. While the 



throws little light upon the cause of the closely related species and varieties, 

 two points that the author has attempted to prove. — Mildred Nothnagel. 



Vegetative vigor and reproduction. — Pieters 2 * has made an interesting 

 contribution to our knowledge of the structural responses of plants to varying 

 chemical and physical conditions. The work of Klebs, indicating that the 

 appearance of reproductive cells is a response to diminishing vegetative activ- 

 ity, and that structures in general represent expressions of the potentialities 

 of an organism, called out by the prevailing conditions for metabolism, has set 

 in train investigations which should be multiplied. Pieters used two species 

 of Saprolegnia and two of Achlyn in his investigations, and a summary of his 

 results is as follows. There is no necessary relation between vegetative growth 

 and sexual reproduction when the available food exceeds J:he minimum con- 

 necessary varies with the species, but in general is in the neighborhood of 

 o. 1 per cent peptone for the production of both sporangia and oogonia. While 

 growing vegetatively, a mycelium may develop tendencies that may affect 

 the number and character of the reproductive organs produced subsequently 

 under different conditions. Of the carbohydrates used, maltose and levulose 

 are especially useful for vegetative growth, and the latter is particularly effect - 



M Sakamura, Tk tsi .-, Cher .lie Kinschniirung der Chromosomen bei Vicia Faba L. 

 Bot. Mag. (Tokyo) 29:287-300. pi. /j, figs. 12. 1915. 



^ « Pieters, A. J., The relation between vegetative vigor and reproduction in some 



