80 University of California Publications in Zoology IVol. 16 



granules of this double blepharoplast complex. The apparent sizes 

 and positions of these granules vary greatly. Sometimes they are 

 separated by distinct spaces and again they are Tua.ssed into one 

 granule from which all the fiagella appear to arise (pi. 11. fig. 27). 

 The flagella are equal in length and are frequently two or even three 

 times the length of the body. 



Extending backwards from the blepharoplast complex are two 

 slender, outwardly convex, hyaline axostyles, which terminate at the 

 posterior border of the body in small chromatin granules from which 

 arise the two posterior trailing flagella (pi. 11, fig. 25). The axostyles 

 show a clear, homogenous structure and appear to have a very definite 

 boundary. They may be more or less widely separated in the body 

 and are frequently crossed in certain aspects. They are not rigid 

 structures, but are very flexible, turning and bending easily with the 

 movements of the protoplasmic body. 



The most characteristic structures of H. intestinalis are the two 

 nuclei. These are situated in the anterior part of the body, immedi- 

 ately behind the blepharopla.st complex (pi. 11, fig. ,25). In the ordi- 

 nary trophozoite these show no definite structure and seem also to be 

 devoid of a nuclear membrane, consisting only of a large club-shaped 

 mass of chromatin material, from 3 to 4 or 5/it in length. The anterior 

 ends of these are often massed together with the blepharoplast complex, 

 exhibiting together the general shape of a horseshoe (pi. 11, fig. 27). 

 The proximal ends of the axostyle unite with each other and then pass 

 forward to the blepharoplast complex in a rather broad band which 

 divides again, one half going to each half of the blepharoplast (pi. 11, 

 fig. 40). The two nuclei are attached to the blepharoplast complex, 

 one on either side of the axostyles to which they are not attached. 



The precise relations of the neuromotor apparatus cannot be made 

 out in the ordinary preparations, but in many cases what appears to 

 be eytopla.smic degeneration has resulted in the loss of all the sur- 

 rounding cytoplasm, leaving the nuclei with the attached motor ap- 

 paratus intact, as shown in figure 40, plate 11. These appearances 

 indicate that the neuromotor apparatus is a structural unit (Kofoid 

 and Swezy, IDlSo, b). 



The protoplasm is alveolar with granules closely packed between 

 the alveoli. In very many of the smaller individuals the alveoli are 

 but indistinctly marked off and the granular structure is more con- 

 spicuous. The occurrence is often noted of two large vacuoles in the 

 anterior part, closely pressed between the axostyles and the blepharo- 



