

iQ2o] CURRENT LITERATURE 167 



It is a species little known outside Jamaica, and is restricted there to the 

 mountainous interior. It is one of the plants that live vegetatively for a 

 number of years and then flower and die. Agave americana (" century plant ") 

 is the most commonly cited illustration of this habit. The bamboos are 

 notable for this kind of periodicity, the number of years of vegetative activity 

 before flowering varying widely in different forms. Apparently, when flower- 

 ing occurs, most of the individuals of a region are involved, and presently all 

 the mature plants are dead, and the ground occupied by seedlings. Seifriz 

 had an opportunity to observe the flowering condition of Chusquea abietijolia 

 in 1918, and the records available showed that the previous flowering condition 

 had occurred 3$ years before. The explanation of this behavior is not available 

 as yet, for seasonal factors controlling such long periods are very unlikely. 



J. M. C. 



Mosaic disease of spinach. — Investigations of Jodidi, Moulton, and 

 Markley, 12 of the Bureau of Plant Industry, have shown that "spinach plants, 

 especially their tops, affected with mosaic disease, have a smaller percentage 

 of total nitrate, acid amide, mono and diamino nitrogen, but a somewhat 

 larger percentage of ammonia than normal plants, nitrous acid being present 

 in diseased plants only. This is due to the fact that denitrification takes 

 place whereby nitrates are reduced to nitrites which, reacting on various 

 nitrogenous compounds present in the spinach, bring about elimination of 

 nitrogen in a free state, involving also loss of nitrogen in the form of ammonia.'' 



It will be very interesting to know how generally in physiological diseases 

 of plants and in viris and other disorders denitrification is involved. 13 — Wm. 



Crocker. 



Leaching of nitrates. — Working with uncropped and unmanured soils 

 Russell and Richards 14 conclude that " the nitrate in drainage water accounts 

 for practically all the nitrogen lost from the soil. The uncertainty attaching 

 to the estimated figures and to the actual amount of new nitrogen in the rain- 

 fall deprives the balance sheet of precision, but there is no room for much 

 fixation or loss of gaseous nitrogen. The chief, if not the sole action, in this 

 soil when there is no manure, crop residues, or fresh supply of organic matter, 

 is the production of nitrate. It is in these circumstances that the nitrogen 

 cycle is seen at its simplest. We know from other Rothamsted experiments 

 that the cycle becomes more complex when organic matter is added to the 

 soil, both fixation and loss of nitrogen being then liable to occur."— Wm. 

 Crocker. 



12 Jodidi, S. L.. Moulton, S. C, and Markley, K. S .. The mosaic disease of 

 spinach as characterized by its nitrogen constituents. Jour. Am. Chem. Soc. 

 42:1061-1070. 1920. 



13 Bot. Gaz. 65:199-200. 1918. 



»« Resell, E. J., and Richards K. II. , The washing out of nitrates by drainage 

 water from uncropped and unmanured land. Jour. Agric. Sci. 10:22-43. 1919. 



