S. G. Paine 215 



the fact that during fermentation the temperature usually rises to 120° 

 or 130° F., a moist temperature sufficiently near to the thermal death 

 point of the organism to eliminate this source. The other materials used 

 on the bed, though not free from suspicion, were hardly likely to have 

 introduced the organism, since, as stated in the Introduction, the disease 

 did not appear uniformly distributed over the beds. The water used 

 for sprinkling the beds was deemed to be a likely source. This was 

 taken from the town main and from an old well. Both of these supplies 

 were sampled on two occasions and platings made upon mushroom- 

 extract agar, many colonies of ammonifying organisms developed on 

 the plates and most of these were tested by inoculation upon growing 

 mushrooms, but in no case was there any production of the disease 

 symptoms. Early suspicion fell upon the air as the carrier of the organism 

 since, as stated in the footnote on p. 206, the disease, originating near the 

 doors and windows of the sheds, seemed to be associated with draughts. 

 The litter when removed from the beds was dumped down outside the 

 sheds and some was packed at the bottom of the doors to exclude 

 draught as much as possible ; dust from this litter would be carried into 

 the shed each time the door was opened. A search for the organism 

 upon this material, however, proved abortive. 



The disease commenced to decrease in early June, and towards the 

 end of June had practically ceased to exist. This may have been, and 

 probably was, in large measure due to the rapid growth of mushrooms 

 during this warm period, the organism, though a tremendously vigorous 

 grower at air temperature, presumably not being able to keep pace 

 with its active host. Another interpretation is, however, possible; the 

 onset of the disease in March and its fall in June, coupled with the fact 

 that the sheds were surrounded by fruit trees in a large orchard, drew 

 the author's attention to the synchronising of the disease with the 

 period of fruit-blossoming, and suggested that the cause of the disease 

 might be identical with that of the "Pear-blossom Blight," investigated 

 by Barker and Grove (i) in this country, and by Doidge(2) in S. Africa. 



This disease had not been specially noticed by the grower but practi- 

 cally no fruit set this year and the disease might well have been partially 

 responsible for this failure. 



Comparison w^as therefore made of the morphological and physio- 

 logical characters of the mushroom organism with the published records 

 of those of the Pear Blight organism (i, 2 and 3). In most of these the 

 two organisms seemed to be identical. Through the courtesy of Professor 

 Barker, a culture of the latter organism was obtained and careful com- 



