. Science-gossip . ne-trate through theouter tissues. Theydepend on first gain-ing entrance throughwounds into deadparts of the bark orwood, and, afterliving there for atime as saprophytes,extend into the livingelements, and causetheir death. Truesaprophytes arethose which regu-larly pass throughtheir whole life-history in a sapro-phytic manner. This class of cryptogams are not treated inDr. von Tubeufs book before us, which dealschiefly with the true parasites that undergono part of their development as saprophytes,but live in every stage of existence as para-sites. There are also included th
. Science-gossip . ne-trate through theouter tissues. Theydepend on first gain-ing entrance throughwounds into deadparts of the bark orwood, and, afterliving there for atime as saprophytes,extend into the livingelements, and causetheir death. Truesaprophytes arethose which regu-larly pass throughtheir whole life-history in a sapro-phytic manner. This class of cryptogams are not treated inDr. von Tubeufs book before us, which dealschiefly with the true parasites that undergono part of their development as saprophytes,but live in every stage of existence as para-sites. There are also included the hemi-parasitesand hemi-saprophytes. The former are capable,if need be, of becoming saprophytes for a season, butas a rule they live throughout their whole develop-ment as parasites. The latter usually pass throughtheir lives as saprophytes, but occasionally arecapable of existing wholly or partially as of these may be termed occasional under certain conditions they become parasitic. M. EriciiLoic TvrniN.\ forming white circles on grass stems(From Diseases of Plants.) The Uredineae, or rust-fungi, may be taken asthe most typical of the true parasites. They con-stantly pass through their whole life-history onliving plants, and cannot be cultivated on a deadsubstratum. The same may be said of theErysipheae, or mildews, though their spores notinfrequently reach perfection on a dead substratum,as do also those of Rhytisma and Poly stigma. Ergotof grain and the Sclcyotinia inhabiting berries aretruly parasitic, though they may be in some stagessaprophytically cultivated on dead maybe given as examples of true ii. of Dr. von Tubeufs work is upon Reaction of Host to Parasitic Attack, and will be found of highestvalue to the readerinterested in mal-for mat ions andabnormal growthsamong plants. Indealing with thissubject the authorreminds us that The reaction of thehost to the attacksof parasitic fungi isfairly constant fo
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