A manual of the Infusoria; including a description of all known flagellate, ciliate, and tentaculiferous Protozoa, British and foreign, and an account ... and the affinities of the sponges Volume 1 - Paperback

Purchase of this book includes free trial access to www.million-books.com where you can read more than a million books for free. This is an OCR edition with typos. Excerpt from book: DALLINGER AND DRYSDALE, 1873-1875. E. DE FROMENTEL, 1876. 29 interest and value attached to the results achieved by these joint workers is accomplished through their having struck upon and most successfully followed up an entirely new channel of discovery. Employing the highest and most perfectly constructed modern powers of the compound microscope, and concentrating upon their task an amount of energy and patience scarcely before equalled, Messrs. Dallinger and Drysdaleairected their attention to unravelling the mystery so long associated with the inconceivably rapid production of low flagellate organisms or monads in organic infusions, and more especially such as are so abundantly produced in fish macerations. Taking turn by turn at the microscope, and patiently watching the same forms from hour to hour and day to day, the entire life-history of numerous species of these most minute organisms was now revealed for the first time. Not only was it found that these animalcules increased to an indefinite extent by the familiar phenomena of longitudinal and transverse fission, but also that under certain conditions two or even more individuals of the same species would become intimately united, the result of this fusion or coalescence being the formation of encystments, whose contents broke up into a greater or less number of spore-like bodies, which speedily developed into the parent type. In some cases these reproductive spores were so excessively minute as to defy individual detection under a magnifying power of no less than 15,000 linear, their presence being indicated only by their presenting as they escaped en masse from the investing envelope the aspect of a fluid possessing a slightly higher refractive index than the surrounding water. The power to withstand great vicissitu...