56 Besearches on the Life Histovif of a Cercomonad : 



Lealand's -^^ and A eye-piece.) With this we perceived that the 

 burst cyst was pouring out what at first appeared hke a viscid mass 

 of oily matter, but which, when followed into its more dispersed 

 condition, presented the appearance of minute granulation. A 

 draw-tube 8 inches in length was now put on with the B eye- 

 piece, and on delicate focussing it was palpable beyond all question 

 that a dense mass of granules, inconceivably small, was being 

 emitted from the cyst, as drawn in Plate XXIV., Fig. 11.* This 

 observation appeared to us so important, that it was determined, 

 if possible, to repeat it. This we did : following a pair from the 

 condition drawn in Plate XXV., Fig. 7, to the final bursting of the 

 cyst, as in Plate XXIV., Fig. 11. We have made careful drawings 

 of each stage, but give only the film of the cyst after it had spent 

 itself, in Fig. 12, Plate XXIV. 



It became now a matter of great interest with us to study the 

 future of these infinitesimal spores. With the ^^ ^^^ most accurate 

 observer could not have discovered their presence if he had not pre- 

 viously seen them with the ^V- Indeed, we should have failed 

 wholly to see them but for their enormous aggregation and motion 

 in a mass. A relative idea of their size may be given. The Bac- 

 terium termo of Cohn is familiar to all microscopists. His Bacillus 

 Ulna, a larger form, almost equally so. In Plate XXVI., Fig. 1, a, the 

 former, is drawn as magnified 600 diameters ; the latter magnified 

 with the same power at c, d, e, while at h one of the B. termo at a 

 is magnified 2500 diameters, and at / the Bacillus Ulna drawn at 

 e is also magnified 2500 diameters. Fig. 2 represents a portion of 

 a field under the same magnification with B. termo, and some of 

 the granules emitted from the cyst interspersed. Fine as these 

 dots are, they are all too coarse to be other than diagramatic. 

 This field was now watched without intermission for six hours, 

 when a portion of it in which gradual increase in the size of the 

 granules had been seen was drawn at Fig. 3, the same power of 

 course being employed ; and the increase in size being well seen by 

 a comparison with the B. termo in the field. The increase was 

 now more rapid, Fig. 4 representing the change that ensued in 

 another hour and a half; where there is not only an increase in 

 size, but a tendency to the sub-ovate form of the parent. At the 

 expiration of nine hours (in all), in which the field had never for 

 one moment been un watched, they had grown into the forms shown 

 at a, h, c, d, and e, Fig. 5, and flagella were distinctly seen. How 

 they were acquired eluded our most vigorous research, both then 

 and subsequently. The first movement seen, which was before 

 flagella were discovered, was similar to, but much slower than, that 

 of a watch "balance-wheel"; this was shortly changed into a 



* The relation between the granules and the cyst in size must be considered 

 only approximate ; they cannot be drawn with sulKcicut minuteness. 



