2 The Use of a Simple Microscope. 



places those that are wholly invisible, or but slightly visible in 

 the ordinary way, on an equality with larger structures for the 

 purpose of examination. For instance, if we mix together a 

 handful of beans, peas, wheat, oats, or any other of the larger 

 seeds, any ordinary observer could sort out the different kinds 

 with the naked eye, but to name them correctly would require 

 previous knowledge. But if we substitute for these the grains 

 of three or four different kinds of starch or pollen, no human 

 eye, if unaided, would be able to detect the difference between 

 them, although under the microscope this case would prove 

 quite as practicable as the former. As, however, the objects 

 to be examined f/ecrease in size, so must the magnifying power 

 be zwcreased in proportion ; hence a range of powers becomes 

 requisite ; and as these magnifying glasses vary in description, 

 a short account, with diagrams of some that would prove 

 serviceable to the farmer, has been appended to this paper, 

 together with some few hints to novices and students as to the 

 selection of glasses, the preparation of objects, and the choice 

 of books of reference. It must, however, be borne in mind, that 

 there is no royal road to knowledge, and in this respect the use 

 of the magnifying-glass is not an exception ; its successful appli- 

 cation must he acquired by practice. 



One of the first subjects for which the farmer would probably 

 seek the aid of the magnifying-glass would probably be the 

 seed required for sowing. Every species of seed, and almost 

 every variety of each species, will be found to possess some 

 difference in appearance, either of colour, size, or external 

 marking, that will at once give it a distinctive character. In 

 numerous instances the external tracery upon the testa, or skin 

 of the seed, furnishes not only a beautiful microscopic object, 

 but a means of identification. Henbane, tobacco, poppies, anise, 

 and carraway, will serve as good illustrations of this fact, while 

 each of the different species of silene, or catch-fly, will exhibit 

 not only a strong family likeness, but likewise sufficiently distinc- 

 tive traits to at once determine it specifically. It is almost impos- 

 sible to obtain a correct idea of these characteristics in any other 

 Avay than by actual observation ; hence all the seeds vised by the 

 farmer, as well as those of the common weeds, should be ren- 

 dered familiar to him by examii^ation and study. 



Defects and impurities in samples of seed fall under two 

 heads : — 



1st. Genuine seed, but barren or unripened ; or, again, ex- 

 traneous substances that will not grow, added to increase bulk. 



2nd. Other kinds of seed capable of growth, the plants from 

 which would be undesirable or injurious to the crops or land. 



The strongest plants being derived from fully developed and 



