636 



0. CLIFFOUD DOBKLL. 



January to the beginning of April, and are based upon the 

 cai'eful examination of the rectal contents of over fifty frogs 

 and toads. The original object of the research was to study 

 the life-histories of the small Protozoa (flagellates and 

 amoebee) which occur in this situation. My attention was 

 attracted by the curious degeneration forms, although their 

 true nature was not, for some time, understood. However, 

 after a careful study of fresh material, the complete series of 

 degeneration changes here described became apparent. 



TKXT-riGUKE 1. 



One of the earliest changes which the Opulinaj undergo 

 is a change of shape. Instead of remaining of a flattened, 

 ovate form, they become modified into all sorts of indefinite 

 shapes. Some of these are shown in text-fig. 1, but a great 

 number of other forms may be seen. The drawings are 

 schematic, and merely indicate the kind of thing which one 

 encounters. These forms do not divide in the normal manner, 

 but simply constrict off pieces, apparently at random, of all 

 shapes and sizes. These again divide until small, irregularly 

 discoidal, or ovoid forms are produced which have a length 

 of about 10 ju to SO fi. These usually contain from one to 



