No. 7. DEPARTMENT OP AGRICULTURE. 50S 



tine, first invented spectacles. At about the end of the sixteenth 

 century, lenses were used as microscopes for the examination of ob- 

 jects too minute to be studied with the unaided eye. These lenses 

 were, of course, very crude affairs and were only used singly. The 

 microscopes which are in use today are known as compound micros- 

 copes and are made up of several lenses capable of magnifying an 

 object several hundred times. The first instrument of this kind was 

 invented about 1590, and Galileo perfected one in 1610. Since this 

 period, every year has seen new improvements, and no up-to-date and 

 well equipped laboratory is complete without a microscope. It has 

 only been in recent years that this instrument has been made use 

 of in the analysis of foods and feeding stuffs, and Pennsylvania was 

 one of the first states to take up this line of investigation. 



When the inspection of feeding stuffs was first commenced in our 

 State, it would have been impossible to learn the true character of 

 these products, if microscopical work had not been done. The 

 analysis of a feeding stuff is of course of great importance, but it 

 is also important that the source of protein, fat and carbrohydrates 

 are found, and by a thorough examination of the feeding stuffs, we 

 are able to determine the source and nature of the ingredients. It 

 would seem to those unacquainted with the work that it would be 

 difficult to determine the composition of a mixed feed which has been 

 compounded of several ingredients, covered with molasses, dried and 

 finely ground, but with the aid of a microscope, we are able to magnify 

 each little particle or tissue in any feed to 400 times its actual size 

 if necessary, and as occasion demands, and to tell just what cereal 

 or by-products are used in the mixture. 



Every cereal has a peculiar cell structure different from that of 

 other cereals, and the starches of the many grains differ in their size 

 and shape, and it is as easy for an expert to learn to know these 

 different grades of wheat. There are twenty different kinds of 

 starches which are in this way easily identified by the size and 

 form of their grains. 



The structure of the cell walls of a kernel of wheat grown this 

 year would be the same as that of one grown in Egypt two thousand 

 years ago, and can be easily distinguished from the cell structure 

 of rye, barely or oats. This may be illustrated by the fact that the 

 side walls of the cell in the seed coat of a kernel of wheat looks 

 under the microscope like a string of beeds, while those found in the 

 barely are smooth edged and sinuous, and the cell walls of other 

 cereals are different from these. The starches of the wheat are round 

 and flat, while those of the potato are three or four times as large and 

 shaped like an oyster shell. The structure of the cell walls of the 

 corn cob, rice hulls, peanut shucks and the weed seeds are very 

 characteristic and markedly different from each other when magni- 

 fied about four hundred times, and are easily identified by the prac- 

 ticed eye. 



A few years ago, a large number of feeding stuffs were sold in 

 Pennsylvania which contained rice hulls in a finely ground condition, 

 ranging from ten to twenty-five per cent. Other by-products were 

 used which caused the protein and fat to meet the guarantees, but, by 

 the aid of the microscope this form of adulteration was detected, and 

 as a result during the year just closed, this material was not found 

 to be present in any feeding stuffs sold in our State. By our thus 

 being able to tell of just what the products are composed which are 



