May 1, 1914] 



SCIENCE 



651 



ratios. Others may be satisfied with an elastic 

 view that allows of profound interactions of 

 factors upon one another with their material 

 modification in the " melting pot of cross 

 breeding." 



The lengthy fourth part is an examination 

 of the chief new species of De Vries's cul- 

 tures as to their behavior in crosses, with spe- 

 cial reference to an explanation of this be- 

 havior on the theory of intracellular pangene- 

 sis. An immense amount of detail is pre- 

 sented, well sifted, however, by the summary 

 and conclusions. It is interesting to note that 

 of these new species gigas alone is considered 

 as progressive; hrevistylis, rubrinervis and 

 nanella are regarded as retrogressive, lata and 

 scintillans as degressive, and ohionga as 

 anomalous. 



Finally a fifth part on the cause of mutation 

 gives us the latest statement of De Vries's posi- 

 tion. This part consists of discussions of a 

 number of topics related to other portions of 

 the book or to earlier publications of the 

 author, and constitutes a general summary. 

 " Gruppenweise Artbildung " results from a 

 gradual accumulation of mutations on the 

 part of a species, and hybridization to De 

 Vries includes a very much wider range of 

 phenomena than the types interpreted by 

 Mendelian analysis. 



A comprehensive bibliography of CEnothera 

 experimental literature, a full and very valu- 

 able citation of the crosses that De Vries has 

 personally made among the ffinotheras, and 

 an excellent index complete the volume. The 

 121 text-figures throughout the book are of 

 an unusually high grade, and the 22 colored 

 plates admirably executed. It is greatly to 

 be hoped that the author and publisher will 

 promptly arrange for an English translation. 

 Bradley M. Davis 



Monographia Uredinearum seu specierum 

 omnium ad hunc usque diem cognitarum 

 descriptio et adurnbratio systematica. By 

 P. and H. Sydow. Volumen III., Fasci- 

 culus I. : Pucciniacese, cum 7 tabulis. 

 Lipsiae, Fratres Borntrseger. 1912. 8vo. 

 Pp. 1-192. 



The appearance of the first part of the third 

 volume of the " Monographia Uredinearum " 

 by P. and H. Sydow has been of especial inter- 

 est to mycologists because it has given the 

 first bit of information concerning the classi- 

 fication which the authors are following, or 

 propose to follow, in this work. The two 

 earlier volumes (Vol. I., Genus Puccinia, 

 1902-i; Vol. II., Genus Uromyces, 1910) were 

 entirely taken up with the treatment of two 

 genera, Puccinia and Uromyces, without the 

 slightest hint as to how they were to fit into 

 any general arrangement. It seemed evident 

 from the beginning that these two genera 

 were given preferences on account of their 

 size and popular importance and not because 

 they might appear in that order in any scheme 

 of classification. The correctness of this sur- 

 mise is now well shown. The third volume is 

 begun with a key to the genera of the family 

 Pueciniaceas, a total of twenty-five being re- 

 cognized. In this key Uromyces is number 8 

 and Puccinia number 10. In the preparation 

 of a work of this nature there are many obvi- 

 ous advantages in not being hampered by the 

 publication of a key at the start, before all of 

 the genera are fully studied, which must there- 

 after serve as a guide. The freedom with 

 which these authors began their task they have 

 deliberately relinquished, for they are here- 

 with publishing a key to twenty-five genera 

 although the descriptive accounts to date only 

 cover fully the first sixteen of them. 



To do the monographic work first and follow 

 it with a key will, however, evidently not suc- 

 ceed in eliminating difficulties, as is evidenced 

 by an examination of the present part. For 

 example, one finds that the genera Uropyxis 

 and Diorchidium are recognized in the key as 

 valid, although they have been treated already 

 in previous parts as synonymous with Puccinia. 

 With the exception of these four genera, 

 which have been treated previously, the pres- 

 ent part takes up the genera in the order of 

 the key and proceeds as far as the generic 

 description of Uromycladium, which is the 

 sixteenth genus. 



The genera in the order of their appearance 

 are as follows, Oymnosporangium, Hamasopra, 



