There is nothing more interesting to the Horticulturist than the subject of vegetable parasites, especially those of low organization known as mildew and moulds, or under the later or more polished name of Bacteria. The relationship between the animal and vegetable world is so close, that we are sure the following note by the Secretary, from the recent Proceedings of the Academy of Natural Sciences, of Philadelphia, will be welcomed by intelligent readers everywhere. Professor Joseph Leidy, it may be remarked, was the first to discover that dreadful pest in raw pork, the Trichinia:

"Apropos of a discovery recently made in a dish of terrapin, the President, Dr. Leidy, communicated to the last meeting of the Academy certain facts regarding the presence of parasites in animal substances prepared as food. The habits of the naturalist often led him to observe things in our daily life which usually escape the notice of others. In our food he had frequent occasions to detect parasites which he preferred to reject, but which are unconsciously swallowed by others. While he liked a herring, he never ate one without first removing the conspicuously coiled worms on the surface of the roes; and he had repeatedly extracted from a piece of black bass or a shad a thread worm which others would not distinguish from a vessel or a nerve. While he did not object to the little parasitic crab of the oyster, he made it a point to remove the equally frequent leech from the clam. It was while eating a piece of ham that he had first noticed the presence of the trichina, which discovery he was the first announce. The presence of such parasites was, doubtless, one of the causes which led Moses to declare the pig to be unclean.

In the hundred tape-worms he had examined, from our fellow citizens, during the past twenty-five years, he had ascertained that they had all been derived from rare beef.

" During a visit to Charleston, S. C, before the late war, there were served at an evening entertainment, among other viands, some nicely browned slices of the drumfish, Pogonias chromis. A friend, informing him that some portions were more gelatinous and delicate than others, had helped him to what he supposed was one of such. On cutting into it he had observed embedded in the flesh a soft mass, which appeared of enigmatic character. The following day he procured from market a drum-fish, on dissection of which he found embedded in the tail several egg-shaped masses, about three inches long and less than an inch thick, which proved to be a large coiled worm, Acanthorhynchus reptans. This it was that gave delicacy to the dainty, and in this instance the parasite seemed to enhance the excellence of the food.

" At another entertainment nearer home he had recently partaken of some stewed terrapin. Taking into his mouth what appeared to be an egg, it produced such an impression as led to its rejection. Seeming so peculiar, he tied it up in the corner of his handkerchief for further investigation. He found, on examination, that it was a membranous bag, containing thirty yellowish white maggots, evidently the larvae of a bot-fly, and resembling those found infesting horses and cattle.

'* The dish of stewed terrapins he suspected to have been a mixture of the diamond-back, Emys palustris, and the red bellied terrapin, Emys rugosa. This is not the only instance of the occurrence of bots in turtles, as Prof. A. S. Packard notes the presence of larvae in the skin of the neck of the box-turtle, Cistudo Carolina. The zoological characters of the recently discoverd larvae were given in detail.

" Mr. Wm. H. Dall referred to an interesting parasite inhabiting the body and extending into the tentacles of the snail, Succinea. They grow to an enormous size, occupying so much of the body of the host as to leave but little room apparently for the intestines. The parasite was quite common in European snails, but he had only recently found it in a Western species. It was identified by Dr. Leidy as the Leuco-chloridum paradoxum".