and Laboratory Methods. 2231 



is sufficiently strong in half an hour, but the preparation may be left in the stain- 

 ing fluid 6 hours without injury. The preparation without washing is dried 

 between filter paper, and then waved to and fro in absolute alcohol so long as 

 color is given off. The removal of the colored precipitate on the preparation 

 can be hastened by wiping with a fine brush. Alcohol containing water must be 

 avoided. The preparation is then brought into pure xylol and afterwards 

 mounted in balsam or, better, in thickened cedar oil. 



Nuclei in general stain blue, part lighter and part darker, part pure blue and 

 part with a tinge of violet. The chromatin threads stain more intensely. The 

 protoplasm of the cell, outside the granulations, show a very diverse staining. 

 The protoplasm of the lymphocytes is mostly bluish, often as dark as the nucleus. 

 Some lymphocytes show a reddish protoplasm. Acidophile granules are gener- 

 ally stained red, neutrophile granules red to blue red, basophile granules are 

 always dark red, many times with a tinge of violet. Ernest L. Walker. 



Massachusetts State Board of Health. 



Methods in Plant Physiology. 



IX. ENZYMES. 



Mention has been made previously of a substance which has the power of 

 converting starch into soluble carbohydrates ; this substance, diastase, is one of 

 a large group called enzymes, or unorganized ferments, in distinction from the 

 organized ferments or micro-organisms. Enzymes in general have the power of 

 producing chemical changes in orgaaic compounds without undergoing change 

 themselves. In the study here outlined diastase is used as a typical enzyme. 



1. Preparation of Diastase. Weigh out 25 g. ground malt and place it in a 

 flask with 100 c. c. of water. (The ground malt may be obtained at any brew- 

 ery.) Shake the bottle occasionally during the next half hour, then turn the 

 contents out into a mortar and grind for ten minutes. Filter off the liquid into 

 a bottle and add a few drops of chloroform, to prevent the growth of fungi in the 

 solution. 



If a purer form of diastase is desired it may be precipitated and dried. Add 

 95 per cent, alcohol to the aqueous solution of diastase so long as it causes a 

 flocculent precipitate, ceasing when it only renders the solution turbid. Filter 

 out the precipitate, wash it with absolute alcohol, and dry in a dessicator over 

 sulphuric acid. This solid is impure diastase, it may be prepared for use by dis- 

 solving in water. 



2. The Hydrolysis of Starch by Diastase. Under the action of diastase starch 

 is first converted into maltose and dextrin and then into dextrose, grape sugar. 

 The steps in the process are probably as follows : 



2C,;HioO-, + H,0=CioHooO„ maltose. 

 Ci2H2 20ii+H20=2C6Hi20,., dextrose. 



The operation of hydrolysis is conducted as follows : Prepare some starch paste 

 by adding 1 g. of potato or wheat starch to 100 c. c. of water. Place the flask 

 containing the mixture on a water bath and keep it at the boiling point for 



