544 



SCIENCE 



[N. S. Vol. XXXIII. No. 849 



Viability of P. radicieola on Ash-maltose-agar 



Siberian pea tree [Caragana 



frictescens) 



Red clover (Trifolium pratense). 



Soy bean (Olycine hispida) 



Sweet pea {Lathyrus odoratus) ... 



Garden pea {Pisum sativum) 



Alsike clover {Trifolium hybri 



dum) 



Bitter vetch {Lathyrus 



Flat pea ( Lathyrus sylvestr 



Red clover {Trifolium pratense), 

 isolated from dried plants sent 

 from Medicine Hat, Alta 



Alfalfa {Medicago saliva) 



Black medick {Medicago lupu- 

 Una) 



Horse bean ( Vicia faba ) : 



Black locust {Robinia pseudo- 

 cacia) 



Honey locust [Robinia viscosa) 

 medium dried to 7 mm. from 

 28 mm 



Dutch white clover {Trifolium 



Years Months 



4 4 4 



4 5 



No colonies on ash- 

 maltose-agar. 

 4 10 10 

 4 2 17 



4 3 



4 I _4 

 No colonies on ash- 

 maltose-agar. 



No colonies on ash- 

 maltose-agar. 



Garden bean {Phaseolus vulgaris) 



Scarlet runner bean {Phaseolus 

 multijlorus) 



Hairy vetch ( Vicia villosa) , me 

 dium dried to 4 mm. from 

 24 mm 



Sweet white clover {Melilotus 

 alba), medium dried to 4 mm, 

 from 24 mm 



No colonies on ash- 

 maltose-agar. 



Studies of Media for the Quantitative Estimation 

 of Bacteria in Water, Sewage, etc.: Stephen 

 DeM. Gage. 



The Variation in Composition of Beef Infusion. 

 — In a former report, the writer called attention 

 to the fact that the variation in the amount of 

 solids in beef infusion made by the standard pro- 

 cedure was as great as or greater than the amount 

 of pepton added in the process of making gelatin 

 or agar media from that infusion. At that time 

 (1904) it was suggested that this error might be 

 considerably reduced if the beef infusion were 

 made up to a constant specific gravity. The rec- 

 ords at the Lawrence Experiment Station show 

 that while the specific gravity of coagulated and 

 filtered beef infusion prepared according to the 

 standard procedure, may vary between 1.100 and 

 1.005, about one half of the samples have a spe- 

 cific gravity of about 1.006, and this value was 

 selected as a standard. Analyses of a large num- 

 ber of samples of beef infusion adjusted to a 



standard specific gravity of 1.006 show that the 

 range of variation in the total nitrogen and in the 

 total organic and mineral matters in solution has 

 been fully as great as when no correction of the 

 specific gravity was attempted. The error in read- 

 ing specific gravity with a hydrometer may be as 

 much as ten per cent. A careful analysis of the 

 records shows that the proportion of samples in 

 which the total solids did not vary more than 10 

 per cent, from the mean was increased from about 

 55 per cent, in the case of samples of the usual 

 beef infusion to over 75 per cent, in the samples 

 of infusion with a constant specific gravity, and a 

 similar increase in uniformity is found in the 

 total organic matters and in the total nitrogen. 

 In other words, the use of beef infusion of a con- 

 stant specific gravity is a step toward media of 

 more uniform composition, and toward increased 

 accuracy in bacterial counts. 



The Influence of Quarts Sand upon Microbial Cul- 

 tures: Otto Eahn. 



The object of this paper is to study the influ- 

 ence of soils upon microorganisms. The decom- 

 position of liquid media (milk, peptone solution) 

 was compared with that of the same liquid ab- 

 sorbed in quartz sand, and great differences were 

 found. Naturally, aerobic processes were greatly 

 increased and anaerobic processes greatly de- 

 creased when the liquid was mixed with sand in 

 such proportion as to allow of abundant aeration. 

 Both aerobic and anaerobic processes were fa- 

 vored, however, when just enough liquid was added 

 to the sand to keep it entirely submerged. This 

 indicates a peculiar influence of the quartz sand 

 upon microbial action which is paralleled by the 

 retardation or inhibition of poisonous effects upon 

 plant roots by mere addition of quartz sand. 

 Surface attraction of the microbial products by 

 quartz sand does not account for this phenomenon. 



Studies in Disinfection of Alfalfa Seeds: J. K. 



Wilson. 



Sterile seeds are desirable if not necessary for 

 the study of the relation of bacteria to plant life. 



Sterile legume seeds may be obtained from 

 ripening pods, but occasionally they are needed 

 when such a supply is not at hand. 



The utility of alcohol, corrosive sublimate and 

 formaldehyde in providing such a supply has been 

 tested on alfalfa seeds. 



Sterility of seeds so treated was tested by in- 

 cubating them in standard bouillon and examining 

 them macro- and microscopically. 



Seeds immersed in 70 per cent, alcohol for 105 



