Communications. 317 



tar from the teeth, and gave such a description of their forms 

 and movements, with drawings illustrating the descriptions, as to 

 leave no doubt that they were the same objects known as the 

 bacteria of today. Nearly a century later, 0. F. Miiller, of 

 Denmark, gave twelve years to their investigation, and discovered 

 three hundred and eighty different forms of these bodies in the 

 fresh and salt water at Copenhagen. Tlaese he named and classi- 

 fied as Monas and Vibrio uuder the general group of Infusoria. 

 Microscopists soon gave a good deal of attention to their investi- 

 gation, but owing to the imperfect instruments in use, little prog- 

 ress was made. There was much conflict of opinion in regard to 

 their place in life, whether they belonged to the animal or vege- 

 table kingdom. Most of the old observers classed them as 

 animals, mainly, because they appeared to have the power of volun- 

 tary, independent motion like animals, and were able to assimilate 

 organized substances. In the following century there was a great 

 increase in the number of observers and in the perfection of the 

 instruments used, yet but little progress was made in settling the 

 questions as to their nature, varieties and proper classification. 

 In 1859, M. Devalue first clearly demonstrated that they belonged 

 to the vegetable kingdom and were related to the Alga?. M. Fer- 

 dinand Cohn, who of all observers has given the most attention 

 to this subject, and whose opinions are regarded as the most re- 

 liable, says that "they belong to the Alg;e, but from the want of 

 Chlorophyl resemble the fungi." Dr. Magnin, a French savant, 

 in summing up the conclusions of M. Cohn, states that: "If 

 there are still differences of opinions among naturalists as to the 

 place of bacteria among the Cryptogams, there is but one opinion 

 as to their vegetable nature." Some still dissent from these views, 

 but they are generally indorsed by the majority of observers. 



Though they are insignificant in size, in numbers and variety 

 they are wonderful. They are to be found everywhere. " Of all 

 beings, they are the most widely diffused. We find them in the air, 

 in water, upon the surface of solid bodies, and in the interior of 

 plants and animals." Some claim that normal blood and healthy 

 tissues are full of the germs ; others are inclined to doubt this, 

 and are disposed to believe that the germs seen in these condi- 



