BOOKS AND CURRENT LITERATURE . 143 



forests and prairies, affording still another reason for placing this contri- 

 bution in the first rank. It is estimated that seven-eighths of the area 

 of Iowa was occupied originally by prairie, this area embracing almost 

 every type of topography and lithological substratum. After listing and 

 discussing the characteristic plant species of the prairie, Shimek considers 

 the relation of the vegetation to various factors, especially to evaporation, 

 which is thought to be the chief determining factor. Careful experi- 

 ments with evaporimeters, coupled with long observation, lead the 

 author to believe that exposure to a high degree of evaporation is the 

 chief cause of treelessness. Rainfall and drainage are not determining 

 factors in Iowa, both frequently being equal on contiguous forested and 

 treeless areas. Prairie fires as a cause are discussed at length and are 

 very properly ruled out as factors of large importance. It seems to the 

 reviewer that the author has proved his case better than anyone who 

 has previously written on the subject, and that the much-vexed problem 

 is nearing solution. The paper closes with an admirable bibliography. 

 The plates are well selected and several of them show a striking differ- 

 ence between the vegetation of opposing slopes, which is clearly related 

 to differences in evaporation. — Henry C. Cowles. 



Uninucleate Aecia. — Students of the problems relating to the sexu- 

 ality of fungi will be interested in a brief paper by Miss Moreau. 1 She 

 finds an aecidial form parasitic on Euphorbia silvatica, which bears aecia 

 with only one nucleus. The mycelial cells are also uninucleate, as are 

 the mother cells, which give rise to the chains of aecia and the intercalary 

 cells. Since she was unable to bring about the germination of these 

 spores, we do not know whether they germinate as normal aecia or as in 

 Eudophyllum. Should Miss Moreau 's observations be substantiated, 

 this will prove to be the first exception to the generally accepted law, 

 that aecia are always binucleate — Frederick A. Wolf. 



iMoreau, Mme. Fernand, Sur l'existence d'une forme ecidienne uninucl66 

 Bull. Soc. Mycol. France, Tome 27: 489-493 (1911). 1912. 



