Note: The most part of the material given to be reproduced is older than 30 years and, as it was not conserved in an ideal condition, it presents blotches, mould, etc. In view of that, we limited the manipulations to a minimum, to avoid a great deviation in the illustration's colors. It has been done the best to improve the images quality, but, in some of them, it was not possible give a better treatment car the operations caused a great prejudice to the colors. In spite of taking the maximum care with these manipulation, the colors of the illustrations could be different from the originals.