876 



SCIENCE 



[N. S. Vol. XXXI. No. 805 



the new water line. The location of villages and 

 the lines of transportation are shown to be 

 closely related to the forms thus described. 

 Some Recent Results in Connection with the Ab- 

 sorption Spectra of Solutions: Habet 0. Jones, 

 Baltimore. 



The absorption spectra of dissolved substances 

 are not simply a function of the nature of the 

 substances, but also of the nature of the solvents. 

 Thus in the case of solutions of uranyl chlo- 

 ride we have one spectrum in water, another 

 in alcohol, still another in acetone and a spectrum 

 in glycerol which is very different from any of the 

 above. The only way in which we can account 

 for these results is in terms of the solvate theory. 

 The different solvents combine with the dissolved 

 substance and form solvates having very different 

 compositions. These affect the resonance of the 

 vibrators that are the cause of light absorption, 

 differently; and, consequently, the absorption in 

 the different solvents is different. 



The second point upon which stress is laid has 

 to do with the action of one acid on the salt of 

 another acid. In terms of prevailing chemical 

 theories, when a salt of one acid is treated with a 

 small amount of another acid, a part of the salt is 

 transformed into the salt of the second acid. With 

 the addition of more and more of the free acid, 

 more and more of the initial salt would pass over 

 into the salt of the second acid. In such solutions 

 we should expect to have the bands of both salts 

 occurring simultaneously, with varying intensity, 

 depending upon the amounts of the two salts pres- 

 ent. The fact is that when a salt is treated with a 

 free acid, we have neither the bands corresponding 

 to the initial nor the final salt present, but bands 

 occupying positions intermediate between those 

 of the two salts; and these bands can be made to 

 occupy any intermediate position by suitably vary- 

 ing the amount of the free acid relative to the 

 salt. This shows that between the initial salt, 

 and the one finally formed, there is a series of 

 intermediate compounds or systems, corresponding 

 to the various positions of the bands. 



The number of reactions showing the above 

 relations is not small, and this raises the question 

 whether chemical reactions in general are not 

 much more complex than is usually represented 

 by our chemical equations, which deal only with 

 the initial and final stages. 



The Propagation of Explosions in Mixtures of 

 Petroleum Vapor loith Air in Tubes: Charles 

 K MuNBOE, Washington, D. C. 



What Constitutes a Species in Agave: Willlak 



E. Tkelease, St. Louis. 



An analysis of the difficulties met with in 

 obtaining flowering and fruiting material in the 

 slow-maturing agaves; in finding spontaneous 

 plants identifiable with many of the garden forms 

 described as species; and in applying vegetative 

 characters consistently and dependably. The con- 

 clusion is reached that though differing much in 

 aspect, species of this genus are reasonably con- 

 stant in their spine and prickle characters— illus- 

 trations being derived from the century plants, 

 henequens, zapupes, mezcots and pulque magueys. 



Suppression and Extension of Spore-formation in 

 Piper betel: Duncan S. Johnson, Baltimore. 

 The interesting feature of the structure of the 

 fiower in this plant is the presence of male flowers, 

 female flowers and flowers bearing the organs of 

 both sexes, on three separate kinds of spikes. 

 But flowers of each sex often bear some rudiments 

 of organs of the other sex. This shows that while 

 some flowers are apparently of one sex only, they 

 really possess, in some degree, the power to de- 

 velop the organs of the opposite sex. In other 

 words, the cells from which the flowers arise are 

 capable of forming the organs of both sexes, and 

 the fact that one sex only is formed is probably 

 due to some influence, internal or external, affect- 

 ing the cells at the time that the flowers are being 

 initiated. 



Experimental work on certain plants has shown 

 that a change in the light or soil supplied to 

 apparently unisexual individuals may cause the 

 organs of the other sex also to appear. This 

 seems clear evidence that both sexes may really 

 be present in all apparently unisexual plants, but 

 that sometimes one, sometimes the other of these 

 is suppressed or fails to become evident. The only 

 plants of which this seemingly can not be true 

 are those well-known unisexual plants like the 

 sago palm, cotton-woods and willows, in which 

 each individual bears only male flowers or only 

 female flowers year after year, throughout the 

 life of the plant. Another case is that of one of 

 the mosses, in which it has been shown by Noll 

 that the sex remained constant for thirty genera- 

 tions when male or female plants are propagated 

 by budding. 



A Method of Using the Microscope : N. A. Cobb, 



Washington, D. C. 

 The Use of the Hydrometer in Phytogeographic 



Work: John W. Habshbeegeb, Philadelphia. 



