A few names besides Hardenpont stand out prominently and must be mentioned. Of these, Van Mons is best known. Jean Baptiste Van Mons, 1765-1842, was a pharmacist, physicist, and physician, one of the savants of his time, who, late in the eighteenth century, under the potent spell cast by Hardenpont's work, began to breed pears. Space forbids an account of Van Mons' experiments. Suffice to say that he introduced more than two scores of pears having lasting merit, and that in the height of his career he had in his "Nursery of Fidelity" at Louvain, eighty thousand seedlings. Van Mons outlives in fame the Belgian pear-breeders of his time because he propounded a theory for the origination of new varieties of plants, and this in its turn is famed as the first complete system of plant improvement. Van Mons contributed but little of direct value to plant-breeding, but indirectly he gave a great impetus to breeding pears and to the culture of the pear, more especially in America, and we must therefore glance at his theory and trace more in detail its influence on American pear-growing. Van Mons' theory, in brief, as expounded in various papers, is: A species does not vary in the place in which it is born; it reproduces only plants which resemble itself. The causes of variation are changes in soil, climate, or temperature. Whenever a species produces one or many varieties, these varieties continue to vary always. The source of all variation, which is transmissible by sowing, resides in the seeds. The older a variety, the less the seedlings vary, and the more they tend to return toward the primitive form, without being able ever to reach that state; the younger or newer the variety, the more the seedlings vary. In putting his theory in practice Van Mons took the first seeds from wild plants or those little improved, from which he grew seedlings, and from these the seeds were taken from the first fruits to ripen for new sowings. This practice he repeated generation after generation. Thus, it is seen that Van Mons was an early apostle of selection. He is said to have distributed over 400 varieties, about 40 of which are still under cultivation. It is to be feared, however, that Van Mons' theory was preconceived without experiment or even observation for a foundation. He devoted a life of most admirable zeal to verifying and developing this vision of his early years with some material reward it is true, but with a better foundation his prodigious labors would have yielded greater direct results in improving the pear. Still, the indirect results, his influence on the pomologists of two continents, even though they did not subscribe to his theories, was more valuable than the work of one mind and one pair of hands could possibly have been.