BOOKS AND CURRENT LITERATURE 219 



ought not to neglect air currents and ought to deal with light of known 

 quality and intensity. — B.E.L, 



Mutative Effects of Environic Agencies. — The comparative 

 ease and accuracy with which pure cultures of moulds may be made and 

 maintained and the marked changes which these organisms display under 

 the influence of various factors makes them splendid material for the 

 experimentalist concerned with permanent alterations in hereditary 

 lines. Some notice has already been given to the results of Miss Eliza- 

 beth Schiemann who obtained atypic forms of Aspergillus by adding 

 various substances to the nutritive media and obtained departures from 

 the customary types by the use of unusually high temperatures (Plant 

 World 16: 123, 1913). 



Dr. A. F. Blakeslee has recently reported upon preliminary trials 

 including a large number of cultures of Penicillium in a series of nutrient 

 media numbering over three hundred combinations, and in the examina- 

 tion of 22,000 colonies he found 25 or 30 aberrants. He says of these 

 "Some of these variants are surely temporary conditions, for they 

 eventually tend to revert to the normal type. Others may be more 

 permanent but have not been sufficiently investigated. All, however 

 tend, partially at least, to reproduce the new characters and some have 

 for several sporangial generations kept their characters in gross cultures 

 during the few months it has been possible to propagate them. Many 

 of them would undoubtedly be described as distinct species by specialists 

 in the group" (Ann. Rep. of the Director, Dept. of Exper. Evol. Carnegie 

 Institution of Wash, for 1913, pp. 103 and 104). 



Blochwitz has recently contributed further to our knowledge of the 

 possibilities of the inductive action of external forces by some results 

 concerning the origin of new species of Aspergillus by unusually intense 

 light exposures. The effects were cumulative and the most striking 

 feature was the gradual elongation of the conidiophores which finally 

 increased to 10 mm. in length as contrasted with the average normal of 

 1 to 2 mm. The brief notice of this work (Berichte d. deut. bot. Ges. 32 : 

 Hft 2. 100.1914) does not make it clear as to the permanence of the new 

 forms or as to their behavior in illumination of intensity comparable to 

 ordinary daylight. Some care was taken however to distinguish between 

 light and heat effects.— D.T.M. 



Sandhills of Nebraska. — An ecological study of the vegetation of 

 the sandhill region of northern and northwestern Nebraska has been 



