of new matter endowed with living properties. The question is thus stated: "It must be considered to turn almost wholly upon the possibility of the de novo origin of bacteria; since, if such a mode of origin can be proved for them, it must also be conceded for other allied fungoid and algoid units. Evidence, which is of the most convincing character when looked at from all sides, now shows that bacteria are killed by a temperature of 140° Fahr. Yet similar organisms will constantly appear and rapidly multiply within closed flasks containing organic fluids, although the flasks and their contents have-been previously exposed for some time to a temperature of 212° Fahr."
As it will be impossible in this article to give the details of Dr. Bastian's experiments, we will try to convey to our readers some notion of these living organisms, which it is now claimed can be produced when all germs are destroyed. When a fluid containing an organic substance in solution is left to itself for a time, which may be variable in different circumstances, the infusion gradually becomes turbid, and there forms upon its surface a thin, semi-translucent scum,
a. Minute Specks of Protoplasm from Fine Surface Mud of Fresh-water Ponds; b. Protomœba Primitiva, two Individuals resulting from a Recent Fission; c. Vampyrella Pendula; d. Amæba Porreta, a Form of Protomœba.
or pellicle, that soon thickens into a membrane. If the fluid be observed by a microscope of the highest power, when it first begins to grow clouded, it will be found swarming with multitudes of moving specks or spherical particles (Fig. 1, A),varying from 1/20000 to 1/100000 of an inch in diameter. These specks have been variously named. They have been called "monads," or "mycrozimes," or "micrococci," and are termed by Dr. Bastian plastide particles. They are regarded by him as the primordial particles of living matter, and as giving origin to organisms of a higher grade.
Among these are the infusorial objects known as bacteria (Fig. 1, B). These are minute, rod-like, jointed bodies, varying in size according to