114 VIGNETTES FltniT INVISIBLE LIFE. 



history all their own, which we shall now attempt 

 briefly to describe. 



After long and patient watchings one becomes 

 impressed with a certain leading characteristic in 

 respect of them, and that is their variability of ex- 



FIG. 21. 



A. Sphcerophrya symmetrii. B. Podophrya quadripartita. 



(Immature form.) 



ternal form and appearance. Apparently rigid and 

 definite, they yet turn up in every conceivable ir- 

 regularity of outline, so that classification on this 

 basis becomes a hopeless task. Nevertheless, it has 

 been attempted, with the result of plunging the 

 whole subject into obscurity and confusion ; and 

 while valuable observations are made, yet the 

 charm is broken for the general reader. One result 



