January 27, 1905.] 



SCIENCE. 



145 



throughout a series, while that per unit 

 weight varies slightly. The amount of 

 variation in the last case is far too small, 

 however, to interfere with the use of 

 transpiration as a criterion for estimating 

 relative leaf weight. The conclusion from 

 these tests is simply that soils or solutionis 

 may be compared, in respect to their power 

 to support growik, by means of total 

 transpiration of the plants growing therein. 



A number of studies were presented of 

 the relation of transpiration to absorption 

 of salts in water cultures. In a series of 

 cultures with identical treatment excepting 

 for the use of different solutions, transpira- 

 tion (since it is proportional to area and 

 weight of the leaves, and therefore to 

 growth of the plant) is found to be propor- 

 tional to the amounts of salts absorbed. 

 But when one culture is grown in a moist 

 air and another in a relatively dry one this 

 relation fails. A moist air (such as that 

 in a bell-jar), as is well known, checks 

 transpiration to a marked degree. It 

 checks absorption of salts to a very slight 

 degree, often not at all. 



Further Notes on the Physiology of Stige- 

 octonium: Burton E. LrviNGSTON. 

 The alga is the same as that on w^hieh 

 the author has studied the effects of ex- 

 tenial osmotic pressure, drying and the 

 presence of cations. The three above- 

 named conditions cause filaments to assume 

 the palmella form. It is now found that 

 the effect of low temperature (2° to 10° C.) 

 is nearly identical with that of the mineral 

 poisons. Thiis the palmella form is pro- 

 duced from filaments but zoospores are not 

 inhibited, although there was no stimula- 

 tion of zoospores observed. 



In sea-water the alga lives and grows 

 slowly as the palmella form. In sea-water 

 diluted with distilled water to one hundred 

 times its volume the same response occurs, 

 showing that, although natural sea-water 



has an osmotic pressure high enough to 

 produce the change, yet there is present a 

 poison which will produce the same eft'ect 

 without the physical stimulus. It is ap- 

 parent from the studies on metals that this 

 poison must be either anionic or organic in 

 its nature. 



Further, Avater from peat bogs, although 

 it has no appreciable osmotic pressure, 

 causes the alga to change from the fila- 

 mentous to the palmella form. It is prob- 

 able that here we are dealing with an or- 

 ganic substance in small quantities. The 

 observation is of special interest in con- 

 nection with the xerophytic structures of 

 bog plants, seeming to suggest very 

 strongly that the explanation of such struc- 

 tures lies in the presence in the bog water 

 of some organic poison. The toxic prop- 

 erty of this water is not proportional to its 

 acidity. 



TJie Salt Water Limits of Wild Rice: Carl 



S. SCOFIELD. 



Wild rice {Zizania aquatica L.) is nat- 

 urally a fresh-water plant, and abounds in 

 streams flowing into salt water along the 

 Atlantic coast. An investigation was made 

 to determine the salt-water limits of the 

 plant. Three delta regions were surveyed, 

 and the water both inside and outside the 

 wild rice field was tested by an electrical 

 conductivity method. It was found that 

 where the water surrounding the plants is 

 more saline than the equivalent of 0.031 

 normal solution of sodium chloride, the 

 growth of wild i-ice is nearly or quite in- 

 hibited. 



Notes on the Vegetation of Onondaga Lake: 

 J. E. Kirk WOOD. 



Onondaga Lake is situated in central 

 New York and is known chiefly through 

 the existence of certain salt springs on its 

 shore. These springs impart a salinity to 

 a considerable area of the marshy lowlands 

 about the lake and a conspicuous holophytie 



