218 MISCELLANEOUS EXAMPLES 



Fig. 39, A (x 250). The Euglenas become granular and partially 

 decolourised, and careful examination shows, at first, a dim indica- 

 tion of spherical bodies such as are to be seen in the left hand 

 specimen. These become rather more defined as decolourisation 

 progresses, as shown in B (x 375). These particular embryo 

 Peranemata are distinguished from the embryo Amoebae, from the 

 first, by the number of refractive particles seen in their interior, 

 which seem to enlarge as development proceeds. Such biscuit-like 

 particles are particularly distinct in the right hand specimen of B, 

 but are also obvious in C — both in the encysted Peranemata and in 

 the two free specimens. These latter were active, owing to move- 

 ments of their long and stout flagella, before they were rendered 

 motionless by a weak formalin solution, which unfortunately had 

 the usual effect of causing the flagella to be retracted or curled 

 under the body of the organisms. 



It will be observed that here, as in the case of the Amoebas 

 derived from the substance of Euglense, the spheres, which become 

 organised into Peranemata, on their first appearance are motionless 

 and already fill the Euglena cyst ; and that in the process of organi- 

 sation they neither increase appreciably in bulk nor in number. 

 These facts are thoroughly in accordance with the view that they 

 are products of heterogenesis ; and are equally adverse to the hypo- 

 thesis that the Peranemata, as found, are results of infection. No 

 theory of infection could possibly account for the first appearance 

 of the organisms as motionless, densely packed, green spheres 

 gradually becoming decolourised ; and for the fact that this same 

 change occurred in multitudes of Euglena, when at first not a single 

 free Peranema was to be seen. 



These organisms are, however, sometimes produced from small 

 encysted Euglense in a very different manner, and they then 

 commonly have quite a different appearance, owing, for one thing, 

 to the absence of the large biscuit-like particles which were so dis- 

 tinctive in those last referred to. The encysted Euglena becomes 

 decolourised, except for some few green, brown, or yellow pig- 

 mentary aggregates — or perhaps wholly decolourised. Then the 

 entire mass after a time becomes converted, without segmentation, 

 into a single Peranema, which gradually begins to revolve within 

 its cell. At other times, a single segmentation occurs, and the 

 products become converted into a pair of Peranemata. In Fig. 39, 

 D (x 250), one of these small encysted AmcebcC is seen on the left; 

 next to it, another is becoming decolourised, and in the specimen 



