OF HETEROGENESIS 221 



found six coarsely granular units varying much in size, some of 

 which were exhibiting the same slow, semi-rotatory movements, 

 though no flagella could be detected (Fig. 41, C, x 250). Some 

 refuse granular matter was seen among them, and it seemed 

 probable that some of the Peranemata had escaped, as the cyst 

 was not nearly full. A very similar condition of things existed in 

 another more highly magnified specimen, only in this case the 

 organisms exhibited rather freer movements within the half-empty 

 cyst (Fig. 41, E, X 500) ; and languid movements of their long 

 flagella were distinctly seen. After the application of the formahn 

 solution these flagella, as is generally the case, were no longer 

 visible, and are consequently not to be detected in the photograph. 

 In these two photographs all the stages are shown by which the 

 encysted mass becomes resolved into a closely-packed aggregate 

 of motionless spheres within the thick-walled cyst. Had they been 

 products of infection they should have been preceded by an active 

 stage — which was absent. The active stage came later, with further 

 development of the spheres into Peranemata. 



(j) Transformation of the Substance of Encysted 

 Stylonychiae into Monads and Peranemata. 



Changes very similar in nature, though not quite so varied, have 

 also been traced in another set of matrices which, for about three 

 months, remained without showing any appreciable change. It 

 was only after that period that some of them began to undergo 

 developmental processes, resulting in the production of Ciliates 

 of the kind known as Stylonychia lanceolata. The fully developed 

 matrices were contained in fairly thick cysts, covered with short 

 conical projections, almost exactly like what are figured by Saville 

 Kent in his " Manual of the Infusoria " as pertaining to one of the 

 other representatives of the genus Stylonychia. 



As I have said, these matrices remained for about three months 

 without undergoing any further change. Then, within a few of 

 them, Stylonychiae began to develop, to rotate, and ultimately to 

 emerge from their prison. About the same time that these normal 

 developments of the contents of the cysts were first observed I 

 began also to find other cysts, in which the contents were under- 

 going, or had undergone, certain heterogenetic transformations. 



About ten weeks previously, portions of an Euglena pellicle 

 in which they were found had been transferred by a section-lifter 



