1900J MICROSCOPICAL JOURNAL. 77 



the production of sturdier leaves and more chlorophyU. 

 Cobalt likewise exerts a stimulating influence. Boron, lead 

 and tungsten exert in some cases a stimulating influence. 

 A somewhat similar line of investigation has been car- 

 ried on by Clark in a[)aper on the toxic effect of deleterious 

 agents on the germination and development of certain 

 flamentous fungi (Bot. Gazette 28: 289). Hydrocyanic- 

 acid so deadly to higher vertebrates is much less toxic to 

 less highly organized structures. To moulds it acts as one 

 of the most fatal poisons. (Edocephalum is particularly 

 sensitive to this agent. 



Useful Plants of Mexico. — Dr. J. N. Rose (Contr. 

 U. S. Nat. Herb. 5: 209) is the author of an interesting 

 treatise on the useful plants of Mexico, containing a 

 large number of excellent p'ates. The paper is an ad- 

 mirable contribution to our knowledge of the plants of 

 that country. 



Minnesota Plant Life. — In his preface to Minnesota 

 Plant Life, Prof. Conway MacMillan says: "It has been 

 well said that the main diflBculties with the book on pop- 

 ular science are that, if popular, it will not be scien- 

 tific, and, if scientific, it will not be popular." Prof. 

 MacMillan has certainly succeeded admirably in present- 

 ing scientific facts in a popular style. His literary style 

 is excellect and the matter is treated in a very pleasing 

 manner. The story of plant life is told lucidly, the book 

 contains in addition a superb lot of illustrations. The 

 State of Minnesota has publislied an edition of 10,000 

 copies to be distributed to the public schools of the gtate. 

 There is no doubt that the work will have a large influ- 

 ence in teaching the school children of that state that 

 plants are living things,and not merely to he classified and 

 named. "Certain plant individuals and societies are 

 brought before the reader as having life problems of their 

 own, not as mere material for economic, anatomical or 



