ZOOLOGY. 529 



fold dilution nf ordinary culture media would still afford jierfect jrerniination. 

 Dilutions l>oio\v 1,()(H) times jjave no fjerniination except with very sensitive fungi. 

 The spores of Aspergillus and Botrytis were germinated and dried in filter paper, 

 and after drying for some time attempts were made to produce further growth. With 

 Botrytis no further growth could be secured from spores after drying for 24 hours, 

 while with Aspergillus spores grew readily after drying for 20 days, and after 65 days 

 a new growth was i)niduced in about lialf of the cultures. 



The significance of mycorrliiza, K. Stahl {Jahrb. WIsk. Bot. [Prlngaheim'], 34 

 {1900), Xo. 4, pp. 5S9-6GS, figx. 2; Ann. Agron., 21 {1901), No. 3, pp. 113-135).— The 

 author has made a comparative biological study of the occurrence, distribution, and 

 function of mycorrhiza, reviewing and extending the investigations of Frank, 

 Schlicht, Janse, and others. Schlicht reported the occurrence of mycorrhiza on the 

 roots of 70 out of 105 species of North German plants examined, and Janse states 

 that 69 out of 75 species of plants examined in Java bore mycorrhiza upon their 

 roots. The investigation of the author has greatly extended the knowledge as to the 

 number of plants living in symbiosis with fungi upon their roots. He examined 

 species belonging to nearly every group of the higher plants, as well as vascular 

 cryptogams, and found that symbiosis is of wide occurrence in nearly all groups of 

 the higher plants, except upon those whose roots are submerged or floating, and 

 certain sjiecies of Cruciferte, Cyperacepe, and Polypodiacea?. Upon many plants 

 there seems to be a sort of facultative symbiosis, while in others it is obligate. In 

 the course of his observations, tuberous and bulbous plants were examined, and 

 some of those which contained much reserve material in their bulbs were found to 

 live symbiotically under certain conditions. 



There appears to be an intimate connection between the substratum in which 

 plants are grown and the presence of fungi upon their roots. In soil poor in mineral 

 matter and rich in humus the conditions are most favorable for the development of 

 the mycorrhiza. If the nature of the soil be so modified that the plant can secure 

 its necessary nutrition directly, the mycorrhiza tends to disappear. The author has 

 adopted the term mycotrophic for plants which bear mycorrhiza, and autotrophic 

 for those capable of directly drawing their substance from the soil. It is claimed 

 that the presence or absence of mycorrhiza may be determined by morphological 

 and physiological characters. The occurrence of a well-developed root system, 

 active transpiration, accomi)anied by the excretion of much water, and the presence 

 in the leaves of an abundance of starch, oxalate of lime, and nitrates, characterize 

 an autotrophic plant. Those bearing mycorrhiza have reduced transpiration, the 

 carbohydrates in their leaves are in soluble form, and the circulation of the plants is 

 less active. Mycorrhizas convey organic compounds almost entirely to their host 

 plants, as is shown by the lower ash content of such plants. As has been already 

 stated, the symbiosis is more or less facultative with many plants, although obli- 

 gate with others, and the difficulty attending the cultivation of mycotrophic plants 

 is in inverse proportion to the degree of dependence on the mycorrhiza. 



ZOOLOGY. 



The relation of sparrows to agriculture, S. D. Judd {U. S. Dept. Agr., Dhhion 

 of Biological Siirrei/ Bnl. !.'>, ///>. 9S, jih. 4, Jigx- 19). — In this bulletin the author reports 

 the results of observations on the feeding habits of the various sparrows found in the 

 United States. As a result of this study the conclusion is reached that si)arrows 

 a.se class are of greater value to agriculturists than any other group of birds whose 

 habits have thus far been investigated l)y the Department. They were studied 

 by means of field observations, experiments with captive birds, examination of the 

 stomach contents, and a combination of field vTork with stomach examination. A 



