When typically developed its long tendon passes the knee j oint, turning towards its outer side, and lastly, without being anywhere attached to the knee, it forms one of the heads of the flexor perforates digit, ii.
The latter is slit radially, and the magnetic field is so arranged that it perforates each half of the disk in opposite directions.
Both the oxide and hydroxide dissolve in ammonia to form a beautiful azure-blue solution (Schweizer's reagent), which dissolves cellulose, or perhaps, holds it in suspension as water does starch; accordingly, the solution rapidly perforates paper or calico.
Among these may be mentioned the hairy frog of West Africa, Trichobatrachus robustus, some specimens of which have the sides of the body and of the hind limbs covered with long villosities, the function of which is unknown, and its ally Gampsosteonyx batesi, in which the last phalanx of the fingers and toes is sharp, claw-like and perforates the skin.
Ultimately the apex of the tube comes in contact with the tip of the embryo-sac and perforates it.