As a teacher, besides the power of accurately gauging the character and capabilities of those who studied under him, he had the faculty of infecting them with his own enthusiasm, and thus of stimulating them to put forward their best efforts.
When the free ends of the hyphae emerge again into the air they swell up into spherical bodies which may either fall off and behave as conidia, each putting out a germ-tube and infecting the host; or the germ-tube itself swells up into a zoosporangium which develops a number of zoospores.
Infection in these cases occurs in the seedling at the place where root and shoot meet, and the infecting hypha having entered the plant goes on living in it and growing up with it as if it had no parasitic action at all.
It has been shown especially in the Uredineae and Erysiphaceae that many forms which can hardly be distinguished morphologically, or which cannot be differentiated at all by structural characters, are not reall y homogeneous but consist of a number of forms which are se se s g sharply distinguishable by their infecting power.
The threadworm or Oxyuris vermicularis is a common parasite infecting the rectum.