soluble starch originally contained in this portion of the jelly having been converted into sugar by the action of the diastase secreted by the scutellum of the embryo.

If the jelly below another embryo is examined in a similar manner, but at a later date, it will be noticed that the action of the diastase gradually extends as the embryo develops.

The growth of liquefying bacteria must be guarded against as far as possible in this experiment, or the success of the experiment may be interfered with.

Demonstrate that Carbon Dioxide is Generated during the Growth of the Barley Corn.-Arrange four flasks as in the accompanying illustration so

FIG. 18.-Apparatus for Demonstrating that Carbon Dioxide is Generated during the Respiration of Germinating Barley.

that the first contains a solution of caustic soda, the second a solution of barium hydrate, the third some germinating barley corns, and the fourth a solution of barium hydrate. Connect an aspirator to the fourth flask, and draw a current of air slowly through the flasks. As the air enters the first flask

it is deprived of the carbon dioxide it contains, and this is shown by the solution of barium hydrate in the second flask remaining clear. But as the current of air passes through the flask containing the germinating barley, it mixes with the carbon dioxide generated by the respiration of the growing corn and conveys it to the fourth flask, where its presence is indicated by the formation of a copious white precipitate of barium carbonate.

Demonstrate that Oxygen is Absorbed during the Growth of the Barley Corn.-Introduce a quantity of actively germinating barley into a large, wide-mouthed stoppered bottle, and place in the bottle a small dish containing a strong solution of caustic soda in order to absorb the carbon dioxide generated by the respiration of the growing corn. Close the bottle with the stopper and allow it to remain overnight in a warm room. Remove the stopper and introduce a lighted taper into the bottle. Observe that the taper is extinguished, owing to the oxygen originally present in the bottle having been removed by the respiration of the germinating barley.

Preparation of Malt Diastase.-Digest 100 grms. of air-dried or pale-dried malt with 250 c.c. of 20 per cent. alcohol for four hours and then filter. Add strong alcohol to the filtrate so long as a flocculent precipitate of diastase is formed. Allow the precipitate to subside and pour off the supernatant liquid. Wash the precipitated diastase

by decantation with a little strong alcohol, and afterwards transfer the precipitate to a hardened filter. Wash the precipitate on the filter repeatedly with small quantities of absolute alcohol and transfer both the filter and precipitate to a vacuum desiccator. By dehydrating the diastase in this manner it may be obtained as a light granular powder.

In order to test the activity of the prepared diastase dissolve about 0.1 grm. of it by rubbing it in a small mortar with about 5 c.c. of water, and transfer the mixture to 50 c.c. of a 1 per cent. solution of soluble starch. Keep the mixture at a temperature of 60° (140° F.). The activity of the diastase will be shown by the gradual disappearance of the iodine starch reaction, due to the transformation of the starch into sugar.

When preparing diastase it is desirable to carry on the process as rapidly as possible, since prolonged contact of the diastase with alcohol tends to destroy its activity. The first precipitate of diastase may be redissolved in water and reprecipitated by alcohol if a purer preparation is desired.

Action of the Enzyme Cytase.—Prepare an extract of air-dried malt, or of oats, by digesting 25 grms. when finely ground with about 70 c.c. of cold water for three or four hours. Filter the extract, which contains the enzyme cytase. merse in the extract several very thin transverse sections of a barley corn, and place the vessel containing the solution in an incubator at a temperature of 25° to 30°. In four or five hours examine one of the sections with a microscope, and it will be

observed that the walls of the starch-containing cells are swelling and gradually dissolving away. A complete disintegration of the cell walls should be obtained in about twelve hours, but if the experiment is continued for this length of time it is advisable to add a little chloroform water to the cytase extract in order to prevent the growth of micro-organisms.

If malt is employed for the purpose of preparing the extract used in this experiment, it is essential that it should not have been kiln-dried, for cytase is destroyed by the heat of the kiln. For a similar reason kiln-dried oats should not be used.

An Experiment to Determine the Loss in Weight occurring during the Conversion of Barley into Malt. The loss in weight which occurs in the malting of any special steeping of barley is often difficult to determine in the ordinary routine of malt-house work, as it entails the weighing-up of the finished malt under conditions which are usually inconvenient. A measure of the loss may, however, be made in the laboratory in the following manner :

Average samples of the barley, as steeped, and of the screened malt made from the barley, are required.

Count out 1,000 corns from each sample, and weigh them accurately. The figures thus obtained express the weight of the barley and the weight of the malt obtained from a similar weight of barley. Calculate from these figures the yield of malt from 448 lbs. (or 1 qr.) of the barley. Calculate also from the same figures the percentage loss in weight of the barley when malted.

Note that the loss determined is only in part due to a loss of solid matter during malting, because barley always contains considerably more moisture than finished malt. In order to estimate the true loss of solid matter due to root-growth, respiration, and extraction by steeping water during the malting process, determine the moisture in the samples of barley and malt. From the figures thus obtained and those previously determined, the amount of solid matter lost is readily calculated.

TECHNICAL EXAMINATION OF MALT.

This is a convenient time to study the ordinary technical methods of examining and valuing malt. Practical experience under the guidance of an expert is essential. As a general guide to the student his attention is directed to the following points :

1. The general appearance of the sample, and the kind and character of the barley from which the malt has been made.

2. The "modification" or relative tenderness of the sample.

3. The "condition or relative dryness of the sample.

4. The flavour of the sample.

5. The regularity of growth. (In order to practise the eye in judging this character it is useful to separate 200 corns from a sample of malt into four classes of "still corns," half-grown, three-quarters