6o 



Scientific Proceedings (103). 



failure completely to empty the bladder at either the beginning or 

 end of the period. Such errors may be reduced by basing the 

 output calculations on the creatinine content of the sample, 

 rather than the time over which it is collected, since Shaffer has 

 shown the hourly creatinine output to be constant throughout 

 the 24 hours, e.g., if the creatinine content of the sample analyzed 

 is 1/20 of the individual's known daily creatinine output, the 

 urea and volume output are calculated to a 24-hour basis by multi- 

 plying by 20. 



35 (1495) 



Enzymes of pollen. 



By Julia Bayles Paton (by invitation). 



[From the Osborn Botanical Laboratory, Yale University, New 



Haven, Conn.] 



Pollen enzymes must be very important in rendering stored 

 food available when pollen germinates, in facilitating the passage 

 of the pollen-tube through the pistil, and in stimulating the de- 

 velopment of the embryo and maturing of the ovary. 



Moreover pollen anaphylaxis is now regarded as the cause of 

 socalled hay-fever and other forms of pollen poisoning. Pollen 

 enzymes may be concerned in these reactions, and the proteolytic 

 enzymes may affect the stability of the pollen-protein solutions 

 used in pollen vaccination. 



Yet in spite of the significance of these enzymes few experi- 

 ments in regard to their nature have been reported, and none 

 recently. Erlenmeyer (1874) found amylase in pine pollen. Van 

 Tieghem (1886) reported invertase in hyacinth, narcissus, wall- 

 flower, and violet. Rittinghaus (1886) made observations which 

 indicate the presence of the cytase. J. R. Green cites amylase 

 in pollen tubes. Strasburger (1905) mentions diastase and in- 

 vertin in grains prior to germination. Kammann (1912) found 

 proteases, diastases, catalases, and lipases in rye pollen. 



Although it has been assumed that pollen tubes digest their 

 way through the style there seems to be no experimental evidence 

 as to the exact nature of this enzyme action. Histological exami- 



