Of heterogenesis have limited themselves to cases of microscopic animals and plants, and in most cases, the observations that they have brought forward have been explained by minuter observation as cases of parasitism.
We may now examine the exchange " futures " in minuter detail.
This minuter study had two origins, one in the researches of the medical anatomists, such as Fabricius (1537-1619), Severinus (1580-1656), Harvey (1578-1657), and Tyson (1649-1708), the other in the careful work of the entomologists and first microscopists, such as Malpighi (1628-1694), Swammerdam (1637-1680), and Hook (1635-1702).
This structure can be rendered visible by superficial etching with dilute acid; and as the minuter crystals dissolve more quickly than the larger ones, the surface assumes a frosted appearance (moiree metallique).
In the subject of diseases of the skin much has been done, in the minuter observation of their forms, in the description of forms previously unrecognized, and in respect of bacterial and other causation and of treatment.