Note 67 — Chapter II

Difficulties formerly associated with the microscopic examination of flagellate forms of infusorial life have been overcome by improvements in the objectives, by the knowledge gained of the monad groups, and by the exhaustive researches of Drs. Drysdale and Dallinger, whose joint investigations were published in the Journal of the Royal Microscopical Society, 1873-75. By employing the highest and most perfectly constructed powers of the microscope, and devoting an enormous amount of time and attention to unravelling mysteries so long associated with the production of the lowly organised flagellate organisms, monads, and patiently watching hour by hour, the life-history of numerous species of these minute infusorial animalcules were obtained. Not only was it discovered that these organisms increased indefinitely by fission, but that under certain conditions two or more individuals were united into encystments, and whose contents broke up into a greater or less number of spore-like bodies, were speedily developed into the parent type. In the examination of these minute bodies, it has been found that talc-films, that is, talc split into extremely fine laminæ, offer the best kind of cover, in fact, supersede ordinary glass covers, and possess an advantage, that of bending readily, thus permitting the objective to be brought close down upon the object.