1900] MICROSCOPICAL JOURNAL. 47 



first plugging the water ducts and afterward invading par- 

 enchymatic tissue. The results of Dr. Smith's work are 

 not only interesting from the standpoint of vegetable 

 pathology hut show how important it is to follow out the 

 life-history of many of our fungi by making careful cul- 

 tures. Many of the species cannot be determined from 

 the descriptions furnished by Saccardo and other writers. 

 The work is accompanied by a large number of excellent 

 figures. 



Lactic Acid Bacteria. — Weigmann (Centralbl. Bakt. 

 u. Parasitenk. II Abt. 5 : 859) in his concluding article 

 on an attempt at the classification of the lactic acid bac- 

 teria concludes that a large number of the so-called species 

 are but forms of a single species. Many of these forms 

 are described as cocci or short bacilli. It is difficult in 

 many cases to be able to say whether such forms are cocci, 

 or bacilli. It is difficult to separate on morphological 

 grounds, but they are to be distinguished on a physiologi- 

 cal basis. Diagnostic characters for the separation of 

 species are to be found in such facts as the growth of col- 

 onies on the surface or down in the medium. Some 

 species are very sensitive to the presence of oxygen. On 

 this basis he divided the lactic acid bacteria into two 

 groups. 



Nitrification. — Bailey (Centralbl. Bakt. u. Parasitenk. 

 II Abt. 5: 857) considers it doubtful whether any or- 

 ganisms of nitrification are able to live entirely on min- 

 eral matter. He thinks the purity of mineral culture has 

 been overstated ; enough organic matter will get into the 

 medium during the process of making to furnish matter 

 for their growth. 



Mineral Nutrients of Plants. — Dr. Oscar Loew in 

 a paper on the Physiological role of mineral nutrients 

 (Bull. U. S. Dept. of Agrl. Div. of Veg. Phys. and Path 

 18:60) gives au excellent summary on the important sub- 

 ject. In regard to calcium and magnesium he concludes 



