41 



Ehrenberg, in the progress of his observation of the Infu- 

 soria, gradually discovered the organs of mastication and 

 degkitition, the alimentary canal, the apertures of the body, 

 a muscular system, sexual organs, eyes, vfcc. It is not to 

 be supposed that all these organs are to be found in every 

 animalcule, nor is it probable that a common observer would 

 perceive them in every case in which Ehrenberg has pointed 

 them out. He possessed uncommon powers of observation, 

 and united with them great ingenuity and skill in manipu- 

 lation. He has been especially successful in drying and 

 preserving the uncoated or illoricated infusoria, so as to 

 exhibit not merely the outlines of their forms, but also the 

 most delicate cilia which otherwise were hardly percep- 

 tible. 



With the exception of Professor Bailey of West Point, 

 who, since the year 1841, has made, in Silliman's Journal 

 of Science, very ample and interesting communications 

 respecting the American Bacillarige, no one has given to the 

 public any notice of the American Infusoria ; it is to be 

 hoped, therefore, that one who is so well qualified for the 

 task, as Prof. B., both by his experience and habits of 

 observation, will complete the work he has so successfully 

 begun, and make the other portions of our infusorial tribes 

 as well known to the naturalists of Europe, as he has 

 already made the different members of the Bacillarian 

 family. 



To the members of the Essex Institute, whose activity 

 and zeal are doing much for the advancement of natural 

 science, it is hoped the fSllowing list of infusorial objects, 

 found in and near Salem, Mass., however imperfect or 

 incomplete, msLj not be altogether an unacceptable offering. 

 It is placed "at their disposal, in compliance with their 

 request. It is the result of a series of observations com 

 menced in the year 1835, and pursued as the occupation 

 and amusement of leisure hours, without reference to any 

 scientific purpose. As "Pritchard's Natural History of 



ESSEI INST. PROCBED. 6. 



