190 REPORTS ON THE STATE OF SCIENCE.—1917. 
Carry out a like series of operations with the starch you have prepared from 
flour. 
Examine starches from different sources under the microscope—note the effect 
of iodine. 
Test arrowroot, sago, tapioca, macaroni, vermicelli, for starch ; also try 
if you can extract gluten from these materials. 
The presence of starch, in considerable quantity, in important feod materials, 
having been thus established and something learnt of its properties, the part 
it plays in cereal grains may be considered. 
What happens to the seed when it germinates and a plant grows out of it? 
Some information will have been gained already on this point. The gradual 
disappearance of the starch will have been noted. By tasting grains which 
have been soaked in water and then kept for various periods, the development 
of a sweet taste will be noticed. Malt may then be introduced and an account 
given of the way in which it is made and what it is used for. Malt should be 
made by steeping barley in water during... . hours, then keeping it and 
allowing it to germinate until the young plantlet is about .. .. inches long, 
after which it is dried at a temperature not exceeding....C. The appearance 
of the starch grains of the malted and unmalted barley should be noticed under 
the microscope. Then equal quantities of barley and of malt which have been 
ground in a coffee mill should each be mixed with about... . times their 
weight of ordinary water and the mixture allowed to stand .... hours. It 
would then be discovered that in one case the starch disappears. The liquids 
should be examined and the weights of equal volumes (the relative densities) 
contrasted with that of water. Known quantities should be evaporated in 
weighed dishes on the water bath, in order that the weights of matter in solu- 
tion might be determined. It would thus be discovered that the starch is 
changed into a soluble sugar-like material and the disappearance of the starch 
from the seed during germination would be explained. 
Foster’s ‘Primer of Physiology’ (Macmillan & Co., Ltd., 1s.) might be 
studied at this stage with advantage and the nature of the stomach and 
intestines made clear. At some time also the stomach and the intestines of a 
freshly killed rabbit should be laid bare before the class and their character and 
arrangement fully explained. 
The children might then be asked—What happens to the starch in our food ? 
What is done with it?—It is first chewed in the mouth and becomes mixed 
with spittle or saliva, is it not? Does this latter produce any effect on it? 
Try! Spit freely into a test tube half full of solidified starch paste prepared 
as directed; mix the starch and saliva well together with the aid of a light 
wooden rod which you have made for the purpose. Plunge the tube into a 
‘water bath kept at about . .. C.; examine it at intervals. Repeat the experi- 
ment but first spit into the test tube and then plunge it into boiling water; 
after about five minutes’ heating add the starch and digest the mixture: at the 
same time digest a mixture of starch with similar unheated saliva. Also make 
comparative experiments in a similar way with unboiled and boiled malt-extract. 
It would then be discovered that starch is rendered soluble by something 
which is present both in malt-extract and in saliva—something, moreover, which 
is rendered inactive by heating to near the boiling point of water. This sub- 
stance has been named Diastase. 
The importance of the change thus undergone by starch when ‘digested ’ 
with the aid of the diastase either in malt-extract or in saliva would be more 
obvious when it is realised that starch diffuses with extreme slowness into 
water and that it does not pass through wet bladder or vegetable parchment, 
whereas the sugar which is formed from it on digestion, like ordinary sugar 
and salt, diffuses readily. : 
Our starchy food is cooked either by baking or by boiling it—what is the 
effect on the starch of baking and boiling ? 
When heated in the oven, as in baking bread or pastry, flour is browned 
and may easily be burnt; but flour is more than starch—what happens to 
