July 15. 1919 Carbohydrate Metabolism in Green Sweet Corn 139 



half way around at the base. After the kernels were removed the husks 

 were brought back to place and held by means of rubber bands. For 

 the second set of samples the husks were removed and three rows of 

 kernels taken from the opposite side of the ear. 



The com was thoroughly ground to a mash in a small unglazed mortar 

 and sampled immediately. On account of the short time required to 

 sample the mash it was found unnecessary to surround the mortar with 

 cracked ice. Each set of samples furnished material for the following 

 determinations: Moisture, total sugars as invert sugar, sucrose, free- 

 reducing substances, and starch. The starch was determined as glucose 

 after hydrolysis with dilute acid. 



Moisture. — Approximately 5 gm. of the mash were placed between 

 tared watch glasses ground tight and held together by means of a clamp. 

 After weighing, the cover glass was removed and the material covered 

 with I CO. of alcohol. The samples were then dried to constant weight 

 in a vacuum at 80° C. During the first drying a stream of warm, dry 

 air was passed through the chamber. The watch glasses were clamped 

 together before each weighing. 



Sugars. — When all things are considered, the alcohol method for the 

 extraction of sugars from plant material in general seems preferable to 

 any other yet devised. Since the procedure by different authors varies 

 considerably, a large number of preliminary experiments were performed 

 to determine the best procedure for the alcoholic extraction of sugars 

 from the particular material at hand — namely, green sweet corn at 

 different stages of maturity. The chief problem was to obtain complete 

 extraction of the sugars and at the same time prevent any inversion of 

 cane sugar as well as diastase action. 



These experiments show that there is no appreciable hydrolysis of 

 either sucrose or starch during boiling in 40 or 50 per cent neutral alcohol 

 as long as 60 minutes. However, complete extraction was obtained by 

 a much shorter period of boiling, and consequently the loss of alcohol 

 during extraction is very much reduced. 



The procedure finally adopted was as follows: Samples of 16 gm. each 

 were weighed out into counterpoised 200 cc. Kohlrausch sugar flasks. 

 A small amount of calcium carbonate was added to neutraUze any acids 

 liberated in the mash. It was latp r found that in the case of sweet com 

 this is not as important as in the case of many other plant tissues. The 

 samples were covered immediately with 75 cc. of hot 95 per cent alcohol, 

 the alcohol being previously measured into small boiling flasks and 

 brought to boil on an electric hot plate. 'After the mixture began to 

 boil on the steam bath, 50 cc. of hot water were added. This brought 

 the extraction alcohol down to about 50 per cent. The water 'in the 

 sample was taken into consideration in making this calculation. The 

 foregoing method precluded any possible enzyme action in the weak 

 alcohol while heating up to the boiling point. Small funnels were placed 



