EXAMINATION OF WATER. 747 



division. Nageli takes the same standpoint, and as- 

 sumes the spheroid cell to be the fundamental form, like- 

 wise ascribing to it tb 3 power of elongation and trans- 

 verse division. On the whole, the morphological dis- 

 tinctions of the different forms appear to Nageli to be 

 " too small ; " whilst other investigators maintain the 

 truly specific character of the different bacteria, Fitz 

 distinguishes them as ethyl and butyl. 



It is very generally believed that the forms are 

 quite definite which produce the known fermentations 

 of infective diseases ; that these forms are not changed 

 by grafting upon other substances. That they are con- 

 fined within quite narrow conditions of life has been 

 shown by experiments ; for instance, Koch upon 

 Bacillus antliracis, carbuncle bacillus; Klein, upon 

 Bacillus minimus , in the typhoid of swine ; Klebs 

 and Tommase, upon Bacillus malarice, the excitant of 

 malarial fever; Obermeyer, Heidenrich and others, 

 upon forms of Spirochsetes in relapsing fever, &c. A 

 similar perplexity existed for years in distinguishing 

 Diatomaceee. Many species based upon differences in 

 size had to be abandoned when investigators became 

 acquainted with their developmental history. 



Hallier, a German botanist, having made a careful 

 examination of bacteria, concluded that they were the 

 cleavage of the nuclei of fungoid cells, and he claimed 

 to place them amongst unicellular plants. Consum- 

 ing oxygen and giving off carbonic acid, their mode 

 of respiration certainly implies that they are more 

 closely allied to animals than to plants. The disputed 

 question of the animal or vegetable nature of bacteria 

 was only a very small one amongst the many bones of 

 contention that botanists and zoologists waxed warm 

 over in the early days of the microscope. Some years 

 before bacteria received any special attention, Dr. A. 

 Farre (1842) observed a new and strange form of fever, 

 and this he found was associated with and due to 

 a tangled mass of green- coloured filaments. On closer 

 examination these were seen to belong to the genus 

 Oscillatoriae, the fine threads of which measured about 

 the 1- 5000th of an inch in diameter. Subsequently 



