50 



SCIENCE 



[N. S. Vol. XXXVIII. No. 967 



much of the detail of the work at this experi- 

 ment station. I will here, however, make one 

 very interesting statement, based upon ex- 

 perimental results : In 1911 we had made many 

 plantings of what we call " agar purified 

 wheat seedlings " placing these in soil which 

 we found to be free from the sort of organ- 

 isms which we find to inhabit the average seed 

 grain of wheat. It is not an easy matter to 

 get an agar purified seedling — one which will 

 grow in an agar made of synthetic media to 

 represent the soil, or whose food basis consists 

 of soil solution, in such manner that neither 

 bacteria, fungi, or other organisms are found 

 to be present in association with the roots. 



When we were finally able to produce such 

 agar-purified seedlings, they have been trans- 

 planted. In one set of such plantings in 200 

 lots, the average crop of wheat from such 

 purified seedlings was 11.07 heads per seed 

 produced on an average of 17.24 stools per 

 seed. The heads thus grown were of rather 

 perfect form and gave an average of 21.8 

 grams of nice plump wheat per plant while an 

 untreated seedling of the same pure-bred strain 

 of wheat, selected to the same perfect form 

 and planted on the same day on the same soil 

 gave an average of 6.11 heads on 8.5 stools 

 and an average of 4.7 grams of seed. 



It would make this piece of correspondence 

 too extended to give other data of other types 

 of seedling purification, seed treatment and 

 soil treatment. These will not be given until 

 published in tabular form in^our regular sta- 

 tion bulletins, but I may say that we have 

 found that in a soil which has sufficient fer- 

 tility to produce a crop, bacteria do not appear 

 to be particularly needed so far as that indi- 

 vidual crop is concerned, while there are cer- 

 tain parasitic and semi-parasitic mold-lime 

 organisms which love the soil and the seed 

 which are particularly detrimental and repre- 

 sent the chief crop-limiting factor aside from 

 mineral elements and atmosphere. 



There was a time when the bacteriologists 

 thought they could tell safe or potable water 

 by making counts of the number of organ- 

 isms present. So now, there seem to be quite a 

 few who think they can tell a productive soil 



by the number of organisms that are present 

 therein, or by the amount of ammonification 

 that may be or may not be taking place 

 therein. It does not seem to be true with re- 

 gard to either potatoes, flax or wheat. It 

 made a material difference what kind of or- 

 ganisms were in the drinking water, so also 

 it makes a material difference what kind of 

 microorganisms are in the soil, and I have 

 been unable to find that the amoebae or their 

 allies are particularly harmful or beneficial as 

 associated with wheat cropping. There may, 

 however, be some destructive fellows among 

 them. 



In making these statements, I would, of 

 course, not be misinterpreted as assuming that 

 bacteria do not have a useful place in the 

 formation of plant food in the soil, nor would 

 assume that, to a certain extent, amoeboid or- 

 ganisms may not in part affect this develop- 

 ment, but after a very careful reading of " In- 

 vestigations on Sickness " in soil by Eussell 

 and Golding in Journal of Agricultural Sci- 

 ence, Vol. v., Part 1, and the report of Messrs. 

 Eussell and Hutchinson on " The Effect of 

 Partial Sterilization of Soil on the Production 

 of Plant Pood," as well as their original article 

 on the same subject, October, 1909, in Journal 

 of Agricultural Science, Vol. V., Part 2, I am 

 unable to see that their experiments in any 

 way prove a relation between amoeboid activ- 

 ity and bacterial inactivity, nor can I see that 

 there is any justification in the assumption, 

 that their studies in sewage-sickness show 

 any feature characteristic of cereal sickness 

 in arable soils. A sewage-logged soil is, at 

 best, a poor analog of a cereal-sick arable soil. 

 While no one can doubt that bacteria are the 

 chief active agents in the preparation of plant 

 foods from the rough organic remains of ordi- 

 nary cropping refuse, that is one problem, and 

 crop deterioration, as such, is another, which 

 is superimposed upon the primary conditions 

 of soil fertility. The crop deterioration prob- 

 lem is probably a problem of crop sanitation 

 as involved in infectious disease. 



h. l. bolley 



North Dakota Agricultural College, 

 May 15, 1913 



