﻿1016] CURRENT LITERATURE 443 



had already noticed that temperature affects the rate of cell division, and con- 

 sequently he carried on his experiments in a large thermostat at a constant 

 temperature of 25 0 . The most extensive investigation was made upon the 

 root tips of seedlings of Vicia Faba. From 7:00 P.M. to 11:00 p.m. mitoses 

 are slightly more frequent, and about 4:00 p.m. there is some diminution in the 

 number. Roots of Zea Mays showed a uniform rate of mitosis throughout the 

 24 hours. Stem tips of seedlings of Pisum sativum, grown in the dark at a 



and 1:30A.M. By 3:00A.M. the mitoses were much less frequent, and con- 



of seedlings of Zea M ays, grown under the same conditions, begin to show an 

 increase in the number of mitoses about 10:00 p.m. and a maximum is reached 



about 8:00 a.m. When the stem tips were lighted from 6: 00 a.m. to 6:00 p.m., 



were lighted from 6 : 00 p.m. until 6 : 00 a.m. and kept in the dark from 6 : 00 a.m. 

 until 6:00 p.m., the periodicity was accentuated; while continuous lighting 

 made the periodicity less conspicuous. 



The general conclusion is that, so far as mitosis is concerned, roots have 

 no periodicity, but stems show it in a marked degree, with the maximum period 

 in the night. It is evident that this investigation suggests further work by 

 those who, like Karsten, have facilities for isolating and controlling factors. 

 While so many observations have been made upon growth, and so many curves 

 have been plotted, the literature does not seem to contain any curves for 

 mitosis. Growth and cell division are two distinctly different phenomena 

 which are often confused, or it might be more nearly correct to say that the 

 cell division has been altogether disregarded.— C. J. Chamberlain. 



Strobilus of Gnetum.— Pearson 16 has made a careful study of the puzzling 

 inflorescence of the Gnetales, and has added much to our knowledge of the 

 facts. Not only have the structures involved been confusing, but the termi- 

 nology as well, for how to apply the terms strobilus and flower has been per- 

 plexing. Calling the unit structure a "flower," and the whole cluster therefore 

 an "inflorescence," the following statement of Pearson's results may be made. 

 He finds that wide differences occur within the same species in the number of 

 staminate flowers produced in basipetal succession at each node, in G. scandens 

 the number of such flowers in a single inflorescence sometimes being as many as 

 3000. The " antherophore " apparently elongates rapidly just before dehis- 

 cence of the anthers, freeing them from the envelope. In G. Giiemon the stami- 

 nate inflorescence "usually bears one or more complete female flowers," and 



from which some or all of the staminate flowers have fallen. In G. scandens, 



16 Pearson, H. H. W., A note on the inflorescence and flower of Gnetum. Ann. 

 Bolus Herbarium 1:152-172. pis. 24-26. 1915. 



