84 University of California Publications in Zoology [Vol. 18 



possible sexual phase as yet undetermined may be suggested, but no 

 proof is as yet available of the validity of this hypothesis. 



Internal or Endogenous Budding. — Under multiple fission also 

 the process which we have designated as internal budding has been 

 included since it is regarded as a modified form of multiple fission 

 (fig. 12). In this large flagellated form a number of small zooids 

 can be counted. It was of the greatest interest to find that such a 

 flagellate containing numerous zooids still retained intact its para- 

 basal bod3^ Neither the original parabasal nor the flagellum enters 

 into the formation of the zooids. On the contrary, preparations are 

 in hand showing fields wherein numerous discarded flagella usually 

 bearing the parabasal body still attached can be found. Along with 

 these detached flagella (figs.l, 10) are myriads of small zooids result- 

 ing from the process of internal budding. The zooids are not all of 

 the same size. Many minute forms are found containing the two 

 deep-staining structures, the nucleus and the parabasal body. 

 Between these minute forms and the oval spore forms previously 

 described is a complete series of forms varying slightly in size. The 

 c3'toplasm of the small forms called zooids differs from that of the 

 oval spore forms in its staining capacity. The zooids do not retain 

 the haematoxylin as long as the oval spore forms. This is true of 

 the zooids and oval spore forms in the crop, mid-stomach, and the 

 pyloric expansion. 



Previous to the discovery of sufficient stages in this internal bud- 

 ding process to determine its nature, the appearance of so many 

 zooids was most puzzling. Preparation after preparation was exam- 

 ined showing the field literally covered with the minute forms with 

 no clue as to their origin. This is explained by the fact that out of 

 two hundred preparations of the crop only three show the early or 

 beginning stages of the process of internal budding. A knowledge 

 of the feeding habit of the bug and of the time necessary for the 

 ingested spores to develop into mature flagellates would undoubtedly 

 greatly facilitate the investigation of this process. A more detailed 

 discussion of internal budding together with the figures showing the 

 process in all the stages will appear in a later paper. 



Binary Fission.- — Binary fission occurs among the zooids (fig. 7) 

 in the crop and among the flagellated forms in both the crop and 

 pyloric expansion (fig. 24). It probably occurs in the mid-stomach 

 but no record has been made of its occurrence there. If the number 

 of forms in binary fission found in the living material or stained 



