No. 499] 



NOTES AND LITERATURE 



501 



way the operations of rat and sparrow chilis and similar bodies. 



The services of the society will be placed at the disposal of 

 municipalities, boards of health, agricultural societies, shipping 

 and deck companies, and other bodies interested in the suppres- 

 sion of vermin. The society has already received the support of 

 many eminent physicians, hacteriologists and chemists, together 

 with that of agricultural and poultry organizations, public as- 

 sociations and other bodies. 



H. B. W. 



PLANT CYTOLOGY 

 Polar Organization of Plant Cells. — Research in plant cytology 

 has resulted in conflicting views as to the extent of such polar 

 organization of plant cells as is well known for certain animals 

 from the work of Rabl, Van Beneden, Flemming and others. 

 Some of the alga- present clear evidence of such polarity, the 

 best known example being Stypocaulon, which has a center in 

 the form of an aster with a centrosome, present at the side of the 

 resting nucleus and dividing previous to each nuclear division, or 

 mitosis, to establish the poles of the spindle. A similar aster is 

 present at the tetraspore mother-cells of Dietyota. Other alga 1 



at the poles of the spindles, but investigations so far indicate that 

 they are formed de novo with each mitosis and that there are 

 no permanent centers associated with the resting nuclei to give 

 polarity to the cells. 



The research of recent years on the cells (particularly the 

 spore mother-cells) of pteridophytes and spermatophytes has 

 failed to support certain claims for the presence of centrosomes 

 in these groups of plants, and has indicated that their cells are 



