September 1, 1916] 



SCIENCE 



321 



cially true, since the medium used for incuba- 

 tion (Czapek's agar) is very unfavorable for 

 the development and growth of the Mucorales, 

 the group of organisms which had most repre- 

 sentatives among the fungi isolated by the 

 method previously described. 



Organisms Found 



Mucor plumbeus (Bonorden) 



Mucor racemosus (Fres. ) 



Mucor circinelloides ( Van 



Tiegham) 



Mucor hiemalis (Wehmer) 



Zygorhynchus vuillem''rdi 



(Namys.) 



Mkizopua nigricans (Ehrbg. ).. 



Oreen Trichoderma 



Penicillium lu'eum (^Zukal)... 



Penicillium sp 



Pusarium sp 



Sporolrichum sp 



Acrostalarpnus albus ( Preuss.). 

 Cephalosporium acremonium 



(Corda) 



Zygodesmus sp 



Sderotivm 



Sterile White Mycelium 



+ 



To establish the fact whether the mycelium 

 transferred, after the soil was allowed to re- 

 main in contact with the sterile medium, came 

 from spores or from mycelium in the soil, the 

 following test was made. A series of sterile 

 plates containing cool, sterile Czapek's agar 

 were incubated with spores and portions of 

 mycelium from several organisms. The spores 

 were had by shaking some spore material with 

 50 c.c. sterile water, then dipping a sterile 

 platinum needle into the liquid and passing 

 it over the surface of the sterile medium, thus 

 dropping the single spores. The mycelium 

 was transferred directly with a sterile needle 

 from the culture upon the plate. The organ- 

 isms used for this test were several Mucors, 

 Trichoderma? and Penicillia. After twenty- 

 four hours' incubation at 20-22° C. the plates 



2 The garden, orchard, meadow and forest soils 

 came from the College Farm, New Brunswick, N. 

 J., Cranberry from Jamesburg, N. J., the other 

 four soils from the respective station grounds. 



s Indicates presence of organism. 



were examined. Those that were inoculated 

 with the mycelium had quite an extensive 

 growth, the tips- of the hyphae being about as 

 distant from the center of inoculation as in the 

 case where the soil was used as an inoculum. 

 But on the plates where only spores were inocu- 

 lated very minute colonies could be observed 

 with the naked eye; upon placing the dish 

 under the microscope and examining it with 

 the low power, one could see these colonies 

 forming from each spore along the trace left 

 by the needle in the medium. This fact gave 

 reasons to believe that the mycelium develop- 

 ing on the plates from the soil came not from 

 spores, but from organisms that actually live 

 in the soil and produce mycelium there. 



A number of soils of different origin, of 

 different physical and chemical composition 

 and treatment, were used for this investiga- 

 tion. The following table shows the occurrence 

 of the different organisms in the soil, in the 

 form of mycelium. 



The results brought out in the above table 

 are very interesting. Soils of entirely differ- 

 ent textures, chemical and physical composi- 

 tion, soils widely apart from one another, con- 

 tain many organisms which are alike for sev- 

 eral of them. Of course, this refers only to 

 the organisms that have been isolated by the 

 above method and in the few soils studied. 

 Other soils may contain different groups of 

 organisms, as is found in the case of the Iowa 

 and Dakota soils, where only very few organ- 

 isms have been isolated by the direct method. 

 It looks as if soils that are under a relatively 

 similar range of conditions show, to a certain 

 extent, similar groups of organisms when 

 these are isolated directly from the soil. 



Mucor circinelloides, Zygorhynchus Vuille- 

 minii, green Trichoderma, Bhizopus nigricans 

 and Mucor racemosus were found most abun- 

 dantly. The zygorhynchus has been found 

 at all depths from one to thirty inches below 

 the surface, while most of the other organisms 

 were isolated from the upper eight inches of 

 soil. In most samples taken at depths of 12, 20 

 or 30 inches only zygorhynchus would de- 

 velop from the soil upon the plate, with no 

 other organism. The sterile white mycelium 



