30 MUSHROOM GROWING AND SPAWN MAKING. 



It is not possible here to enter into a detailed discussion of the 

 results, but attention is directed to the fact that under ordinary con- 

 ditions Agarictis campestris does not give a copious growth when 

 nitrogen is furnished from an inorganic salt and carbon in the form 

 of the well-known sugars. Calcium hippurate in a solution of the 

 necessary salts has almost invariably given better growth than other 

 organic salts and carbohydrates. In general, casein has been a better 

 source of carbon, or of carbon and nitrogen, than other proteids. 



When the manure is of good quality it furnishes, in pure cultures, 

 a source of necessary nutrients, whether fresh or fermented, whether 

 as a decoction or an infusion (a cold aqueous extract). 



Acid and alkaline me^ia.— Manure which has undergone fermenta- 

 tion for a few weeks is usually slightly acid in reaction. Under 

 certain conditions of fermentation the acidity is increased, and this 

 is probably an important factor in making the manure from animals 

 fed with green foods less valuable for mushroom work. Some acid 

 tests were made of beds which had failed to yield satisfactory results, 

 and in many instances it was found that the acid content was much 

 above the normal. A small series of experiments was therefore 

 instituted to determine the relative amount of acidity or of alkalinity 

 most favorable for the growth of the spawn under pure-culture con- 

 ditions. In this test there were also included several other edible 

 funffi, the results of all of which are included in the table below. 

 These experiments were made in large test tubes, and in such a test 

 it was impracticable to determine absolute acidity or alkalinity, and 

 from the results only a rough qualitative comparison could be antici- 

 pated. Potassium hydrate and lactic acid were used as reagents. 

 The duration of the experiments was one month, and duplicate cul- 

 tures were used in every instance. 



Although the results are not wholly uniform, it may be inferred 

 that in the case of Agaricus campestris a marked acidity of the 

 medium would be unfortunate; Calvatia cyathiforme^ on the other 

 hand, seems to have grown somewhat better, in general, in the more 

 acid media ; Coprinus eomatus grows under a wdder range of condi- 

 tions; and Coprinus atramentarius, in this instance, thrives in an 

 alkaline medium. Further tests on a quantitative basis are required 

 before definite conclusions may be drawn. This matter will also 

 receive further attention when facilities are at hand for undertaking 

 to better advantage than has yet been possible the practical growing 

 of the other species, besides Agaricus campestris^ included in this test. 



