590 SUMMARY OF CURRENT RESEARCHES RELATING TO 



BOTANY. 



GENERAL, 



Including the Anatomy and Physiology of Seed Plants. 



Cytology, 

 Including" Cell-Contents. 



Amitosis in Onion-root.* — H. E. Jordan has studied nuclear divi- 

 sion in the root-tip of the onion, and finds that when the roots are grown 

 in ethereal solutions, there is an almost complete absence of mitotic 

 figures, but that in the periblem a considerable number of nuclei under- 

 go direct division. This result is tbe reverse of that obtained with 

 roots grown in water. It is uncertain whether this is due to direct 

 influence of the ether upon the achromatic spindle complex, or whether 

 it represents an early indication of a degenerative process due to un- 

 favourable environment ; in any case it indicates a superior sensitive- 

 ness in the centrosome and astral associates to unfavourable environment. 



Structure of the Chromosomes and Resting Nucleus. f— A. B. 

 Lee has studied the structure of the chromosomes and resting nucleus 

 in Paris quadrifolia, and finds that the chromosomes of the homotypic 

 telophase are short with broad alveoles, but this alveolization does not 

 occur during the telophase, being usually an interkinesis process. The 

 chromosomes of the resting nucleus are very long thin spiral bodies 

 arranged in a loose group, and appear to be identical with the chromo- 

 somes of the telophase. The author terms the resting stage the " spiro- 

 phase " and subdivides it into three periods, viz. the prospirophase, 

 characterized by the alveolated chromosomes of the telophase together 

 with fragments of elongated spiral chromosomes ; the mesospirophase, 

 with very long thin spiral chromosomes loosely grouped together ; and 

 the telospirophase, with shorter and thicker chromosomes more or less 

 separate from one another. The chromosomes of the telospirophase 

 shorten and thicken, and ultimately form the spireme of the prophase ; 

 during this period three rows of alveoles appear in each chromosome ; 

 and the splitting of these portions during metaphase sets free chromatin 

 material to form the poles of the spindle. The author regards the 

 division of tbe chromosomes as the result of alveolization ; he also applies 

 a new term (spironema) to the loose group of long spiral chromosomes 

 characteristic of the spirophose, and believes that it would be of interest 

 to discover if such a formation during the resting stage is of general 

 occurrence. 



. Cytology of Micropylar Suckers of Veronica.J— Paul Dop pub- 

 lishes a short note dealing with, the cytology of the micropylar suckers 



* Trans. Amer. Micr. Soc, xxxii. (1913) pp. 103-12 (12 figs.), 

 t La Cellule, xxviii. (1913) pp. 265-300 (2 pis.). 

 X Comptes Kendus, clvi. (1913) pp. 1922-4. 



