132 



BOTANICAL GAZETTE 



[FEBRUARY 



* 



degeneration of the respiratory enzymes during this fall, because 

 when dead seeds are placed in germinative conditions the respira- 

 tion again mounts to a high value, giving off 8 . 84 mg. of carbon 

 dioxide per gram of dry weight in 24 hours. It is not known, 

 however, just what percentage of the carbon dioxide given off in 

 the latter case was due to bacterial action. Haas (13) found that 

 the marine alga Latninaria, in the presence of certain reagents, 

 respired more rapidly after death than in the living condition. 

 Maige and Nicolas (17) have done considerable work on respira- 

 tion in correlation with the state of turgidity of certain plant organs, 



ir 19 21 23 25 17 29 3! 33 35 37 39 41 43 45 



Fig. 1. — Respiration curve for seeds desiccating at 25 C; mg. of COi given off 

 in 24 hours per gm. dry weight plotted on ordinates; time of desiccation in days 

 plotted on abscissae; great rise in respiration after forty- third day due to placing 

 desiccated seeds (dead at time) under favorable germinative conditions. 



as buds, leaves, and embryos. They find in material taken directly 

 from the tree increased carbon dioxide production with increased 

 turgescence, also for decreased turgescence, and usually an increase 

 in respiration when decrease was followed by an increase. Fig. 1 

 represents the trend of respiration during 43 days of desiccation. 

 The sudden rise on the forty-fifth day shows respiratory activity 

 of seeds after being placed in germinative conditions. 



To determine the respiratory activity of germinating seeds, 

 newly collected seeds were planted in the dark at 25 C. The 

 respirometer used was a 500 cc. graduated cylinder. This was half 

 filled with shredded filter paper, previously well sterilized. The 



