2-tS Dynamic Theory. 



bryo Parameciam, or it may become segmented into two parts, each of 

 which becomes an embryo, or these two may subdivide each into two, 

 thus forming four segments, each of which becomes a }'oung Paramecium 

 inside the cell. After a short time these embryos become active and 

 tumble over each other, and finally rupture the membrane enclosing 

 them and swim out into open liquid. The stages through which 

 they pass are essentially those of the Monads and Amoebae. Their 

 shape when grown is ' ' obovate, slight!}' compressed, ends obtuse, the 

 anterior attenuated and slightly bent like a hook. " Their diameter is 

 about ^ of an inch. They are ciliated and contain one or more 

 vacuoles like Monad and Amoeba. 



The reproduction of the infusorial animalcules is various. In some 

 instances it has been observed to take place by fission, the parent split- 

 ting into two, a slow process said to cover many hours, or even days. 

 In other cases it is by means of ova or germs, which are produced by 

 the conjugation, contact or coupling of two individuals (in certain spe- 

 cies ). This is likewise a slow process, the conjugation sometimes last- 

 ing a week, and the ova appearing two or three days thereafter. This 

 would appear to be a truly sexual conjugation, although there are no 

 sexual organs or parts. We may suppose one of these animal specks 

 to be positive to the other negative, and coupled together by this ' ' polar 

 force" be compelled to mingle their constituents in the production of a 

 third body. 



Another mode of reproduction, which may be a supplement to or mod- 

 ification of the last, is one in which the germ develops inside of and ap- 

 parently at the expense of the parent. Sometimes there are two or 

 three of these germs, and their development causes the death of the 

 parent, and their birth its rupture and dissolution. ( See also the same 

 process in the development of the white blood corpuscles. ) 



As to the manner of the development of these little organisms I pro- 

 pose the following theory : By the process of macerating the hay in 

 cool water, the protoplasm of the hay is soaked out without injury to its 

 vitality ; by which I mean its molecular constitution, by virtue of which, 

 while the hay was green and the protoplasm a fluid, it coursed its way 

 up and down the stalks, like blood pulsating through the veins of an an- 

 imal. When the hay was dried, the constituents of the protoplasm were 

 retained in its tissues entire, minus merely the greater part of its water. 

 In the process of maceration, this water is restored and the protoplasm, 

 freed, floats to the top of the liquid. It is in a new element, but its 

 molecular polarity must be regarded as capable of controlling its aggre- 

 gation of particles into masses, more or less definite in size and shape. 

 While these masses take, in the vascular tissues of the hay when alive, 

 such shape and action as their environment there imposes upon them, it 



