328 Dr Escliricht*s Inquiries concerning 



ral a vain presumption to trace the limits of possibility in na- 

 ture. In the process of reproduction a transparent fluid is 

 seen to exi^de, which, by degrees, becomes more consistent, 

 appears gran ulcus under the microscope, and is finally organ- 

 ized, and even in some instances reproduces the lost organ 

 with its bones, ligaments, muscles, and nerves. In generation 

 by means of eggs, the new individual is formed in the same 

 way out of a shapeless mass of microscopical grains. After 

 such analogous facts, we can never regard it as impossible 

 that an animal of a different species of a more simple struc- 

 ture, or even with muscles and nerves, may arise out of the 

 granulous mass which is produced by the decomposition of or- 

 ganic substances." 



Sect. 2. Exposition of the Phenomena by Generation. — • 

 These assertions of the celebrated professor merit a careful 

 examination. The supposed spontaneous generation is de- 

 clared analogous in its appearances to reproduction, and gene- 

 ration by means of eggs. In order to examine the reality of 

 this analogy, we shall take a review of the phenomena attend- 

 ing these processes, such as they have been observed by mo- 

 dern and highly accurate observers, especially by Dr Schwann 

 of Berlin (Mikroskopische Untersuchungen uber die Ueberein- 

 stimung, &c., Berlin, 1838, 1.), and Professor Valentin of 

 Bern (in the Physiology of Professor Rudolph Wagner, 1839), 

 Dr Schleiden having given the first impulse to the investiga- 

 tion by his elaborate memoir. (MuUer's Archiv, 1838, 1.) 



A formless transparent fluid or substance is first secreted 

 from the parent body, which is called the cytohlastema. In 

 this transparent substance grains of the smallest size appear. 

 These increase first by juxtaposition, and thus small bodies 

 are formed with still smaller central bodies, ''^ nuclei^ — nucleoli;'''' 

 the first, also called cytoUasti by Schleiden, in the analogous 

 parts of plants, the merit of which discovery is due to the 

 celebrated Robert Brown. After this a vesicle arises upon 

 each nucleus, and grows by absorption from the cytohlas- 

 tema. This cytohlastema is now, of course, in a great mea- 

 sure, filled with vesicular bodies, each having a minute body 

 or nucleus attached to its inside, which, again, in its turn, in- 

 cludes one or more nucleoli. These vesicular bodies are called 



