226 



Journal of Agricultural Research 



Vol. XX, No. 3 



80 



HUMIDITY PERCENTAGE 

 70 60 SO 40 30 ZO /O 



samples in 8o, 90, and 100 per cent humidities were not included because 

 of the small number of germinations obtained before the seed was par- 

 tially destroyed by molds. The curve shows graphically that there was 

 a decrease in germination from the uninjured samples in the high hu- 

 midities to those in 30 per cent humidity, after which it increased in the 

 successively drier desiccators but did not reach normal. 



It is also noteworthy, in connection with the data given in Table VII, 

 that no injury appeared, as indicated by the germinated samples, until 

 at some time between two and five days after treatment. Thus, a test 

 of all samples after three days, the results of which were not included 

 in the table because of complications from an unusual growth of Rhizopus 

 in the germinators, showed no visible evidence of formaldehyde injury. 

 The harmful effects were first apparent after five days' storage, where, 



however, molds again interfered with 

 the germination of four of the samples. 

 It will also be noticed in Table 

 VII that the successive percentages 

 obtained show no increasing injury 

 between the 5 -day and 42 -day germi- 

 nations. They differ in this from 

 those of many other experiments 

 (Tables I to IV). 



Some months later this experiment 

 was repeated with some of the same 

 lots of wheat. This second experi- 

 ment differed from the first, so far 

 as was known, only in the smaller 

 quantities of treated wheat placed in 

 each desiccator and in the amounts 

 of sulphuric acid and water mixtures 

 used. Approximately 20 cc. of wheat 

 were put in each desiccator, which was about one-fourth of the quantity 

 used before. One hundred cc. of the desiccating solutions were left in 

 the desiccators for the first 24 hours, at the end of which period they 

 were changed, and 200 cc. quantities of the fresh solutions were sub- 

 stituted and left unchanged for the rest of the experiment. As will be 

 seen from Table VIII, the resulting seed injury was more extreme than in 

 the first experiment and reached its maximum in a more humid atmos- 

 phere (Pi. 39). The explanation for the difference may be the greater or 

 lesser effectiveness of the desiccating solutions, owing to the difference in 

 the quantities used and in the amount of seed dried over each. 



The data in Table VIII show, as do those of the preceding experiment, 

 that the highest humidities allow no injury and that in the lowest the 

 germination percentages are normal also, only the retarded growth giving 



Fig. 2. — Graph showing the relation of humidity 

 of the air to percentage of germination of stored 

 seed in first experiment. 



