Arrangement of the InJ\isorla. 325 



as ^\j of its diameter, it amounts in the Monas termo, having 

 a diameter of ^n^nc'", where the stomach appears as the ^th part 

 of the measurable length of the whole, animal, consequently 

 T « i n'" in diameter, to ^ , ^V o (T of a line or ^ g ^ i ^ q g of »" J^ch, 

 and as there is reason for supposing that the walls of the sto- 

 mach contain vessels, it affords a still further minuteness of 

 atoms. But magnitudes even smaller than these may be 

 pointed out. In the Polygastric infusoria there is an ovarium. 

 The grains of this ovarium are as 40 to 1 in the female of the 

 Kolpoda cuculluSy in others as 80 to 1 ; and they appear to in- 

 crease in fineness as the body diminishes in magnitude. Is it 

 not probable that it is only the transparency and the imperfec- 

 tion of our microscopes that prevents us from observing a si- 

 milar ovarium in the monades, which are similarly organized, so 

 that it cannot be overlooked that there may be young monades 

 contained in the ovum, or which have escaped from it, in which 

 the diameter of the whole body measures only ^qIhq'" ^o 

 ^cJoc'j ^^^ which also are provided with stomachs, which, ac- 

 cording to the same relation, will have a diameter of from 

 iFo'ooc'" ^o 5i(j^(jno '? The walls of these monadal stomachs 

 will be about j^^i^^/' to ^^gj-^/' in diameter. 



By the kindness of Professor Ensler of Berlin, I have been 

 enabled to make many observations with a solar microscope. On 

 viewing the Monas atomus^ strongly filled with indigo, I dis- 

 covered in the intervals the shades of smaller monades, which 

 could not have amounted nearly to joVo" > ^"t which were quite 

 invisible in the water when examined with Chevalier'*s micro- 

 scope, perhaps on account of their transparency. Whether these 

 bodies were the young of the Monas atomus^ or independent 

 species, it follows that ^jj^y'" is not the limit to a size of orga- 

 nic forms which can be distinctly seen. 



Improved Arrangement of the Class Irifiisoria, — Hitherto I 

 had only been able to observe in Irifusoria Polygastrica^ the 

 muscular, digestive, and generative systems. In one genus only 

 of the class could I detect the points of the eyes. Recently I 

 have been (viz. the Englena) able to detect the eye-points more 

 frequently, so that now the genera possessed with eyes can be 

 j^^umerated, comprehending sixteen species. Among these forms 



