XI, B, 1 Mendoza-Guazon: Case of Dipylidium Caninum 



23 



of the same species. Later he kindly showed me some of the 

 internal structures of the segments of this parasite. 



The segments, as mentioned, look like seeds of a melon with 

 the pointed end of one sticking a little into the rounded end of 

 the segment in front of it (fig. 1). Each one of the large, flat 

 segments has about the middle a shallow groove on either side. 

 The size of each of the segments diminishes toward the head and 

 becomes smaller after staining. 



Only one of the parasites has the neck and head, which was 

 buried in the mucosa of the small intestine, so that I had to clip 

 this to preserve the head. This chain has about forty segments 

 and measures after staining 48 millimeters. The head is small, 

 is rhomboid in shape, and under ^ power and No. 4 objective 

 of a C. Zeiss microscope, it shows the retracted rostellum with 

 the four rows of alternating, rose-thomlike booklets and two 

 unarmed and somewhat elliptical suckers which hide the other 

 two (fig. 2). 



Fig. 2. Head and anterior segments of Dipylidium caninum. 



The neck is short and does not show marked segmentation. 

 The largest segment is 3 millimeters in length and 1 millimeter 

 in breadth after staining. 



The mature segments (fig. 3) have a slight convex outline 

 and show a bilateral arrangement of the reproductive system. 

 The genital pores are double and open about the middle of the 

 segments and opposite each other. The ovaries are bilobed. 

 The vitelline glands lie posterior to the ovaries. The vagina 

 is posterior to the cirrus pouch. The testicles are numerous 

 and are found in the meshes of the reticulum of the uterus. 



The vasa deferentia are long, follow a tortuous course, and 

 enter the cirrus pouch which is long and slender. 



In the gravid segments the testes and ovaries disappear and 

 the uterus is broken up into capsules which contain the eggs. 



