180 



SCIENCE 



[N. S. Vol. XXXn. No. 814 



stretching of the stipe at times when light 

 can be used as a directive influence. 



One of the most interesting discoveries re- 

 corded in the book is that with reference to 

 the ejection of the spores from the sterig- 

 mata. It is found that the spores may be 

 expelled ten to thirteen times their own 

 length and that they fall from the gills in a 

 peculiar curve that Buller calls " sporabola." 

 The emission of a powder from polyporoids 

 had been seen before, but as a very rare oc- 

 currence. It has remained for Buller to de- 

 vise by means of a beam of light a method of 

 determining readily whether spores are being 

 discharged or not. Then by observing some 

 mature spores on a section of a gill, he was 

 able to determine that the spores were actually 

 projected, although the actual flight through 

 the air could not be seen. This ejection is in- 

 dependent of hygroscopic conditions, takes 

 place but slowly at 0°, and is stopped by an- 

 esthetics and by lack of oxygen. It is there- 

 fore a phenomenon of protoplasmic activity, 

 not a mere result of hygroscopic tension. 



For the Basidiomycetes the hypothesis is 

 advanced that the discharge of spores is simi- 

 lar to the jerking process described for Empusa 

 by iSTowakowski. It involves the mutual 

 bulging of the walls of the sporidia and the 

 sterigmata, in opposite directions. 



On the side of physics, Buller pushes the 

 matter to a fine point, determining the specific 

 gravity of spores by floating them in diiferent 

 strengths of CaCl, (allowing for plasmolysis) 

 and also determining the rate of fall in the 

 air. The latter was an attempt to verify 

 Stokes's law on the fall of microscopic bodies. 

 The results show a velocity 50 per cent, greater 

 than the computed rate. 



In Part II., the spore dispersal of the As- 

 comycetes is considered. Here the observa- 

 tions of the author lead him to conclude that 

 the explanation of deBary which attributes 

 the expulsion of spores to mere loss of water 

 does not explain the phenomenon of " pufiing." 

 In general Buller is led to believe that the 

 " pufiing " is caused by a stimulus given to the 

 protoplasm in contact with the ascus lid. 



Some of the interesting points in the book 



are: (1) The descriptions of the new Poyn- 

 ting's Plate Micrometer, (2) the figures on the 

 increase of hymenial surface due to gills, (3) 

 the number of spores per sporophore, (4) the 

 specific gravity of various spores, (5) the 

 effect of electric charges on different spores, 

 (6) the persistence of vitality in certain 

 xerophytic species, (7) the summary showing 

 the present status of the work on the nuclear 

 phenomena in the Basidiomycetes and (8) 

 the problems suggested with reference to the 

 relation of insects and spores. 



G. H. Coons 



The Universitt of Nebraska, 



Nebraska Experiment Station 



Experimentelle Uniersuchungen iiber Atom- 

 gewichte. Von Th. W. Richards und seinen 

 Mitarheitern 1887-1908. Deutsche Ausgabe 

 von J. KoppEL. Pp. viii + 890. Hamburg 

 und Leipzig, L. Voss. 1909. Preis M. 35. 

 Theodore William Eichards occupies in our 

 time, with regard to the precise determination 

 of atomic weights, the place which was occu- 

 pied in the first half of the past century by 

 Berzelius and in the second half by Stas. 

 And just as Stas, in his memorable investiga- 

 tion of the atomic weight of carbon, carried 

 out jointly with Dumas, demonstrated the ne- 

 cessity of a new and independent study of the 

 entire problem by his discovery of a not in- 

 considerable error in the atomic weight found 

 by Berzelius, so Richards proved the necessity 

 of his own researches by demonstrating the 

 inexactness of Stas's fundamental value for 

 silver. However, there is also a deep-seated 

 difference between the two achievements: the 

 older discovery was made at the beginning of 

 the new period, and was exploited by Dumas 

 in his usual highly dramatic fashion; while 

 Richards was almost forced, by a series of 

 mutually corroborating deviations, to aban- 

 don the older value, at first regarded by him 

 with complete confidence, and to accept his 

 own unexpected result. This says : Dumas 

 was a thinker of the romantic type, while 

 Richards is a classic, just as Berzelius and 

 Stas were classics. Indeed, atomic weights 

 can be successfully determined only by a clas- 

 sic. Witness Dumas, who undertook it in 



