49^ Cyst-affected Beef and Pork. [part hi. 



somewhat complex details of which will, perhaps, be made clearer by the accompanying 

 semi-diagrammatic sketch. (Fig. 30.) 



The only marked difference between the measle ,of pork and the measle of 

 beef and veal (for calves are found to be much more frequently infected than 

 grown-up cattle) is found in the so-called " head."' The two kinds are provided 

 with small circular discs or suckers. These are well shown in the micro-photograph (No. 8, 

 Plate XXXVII), representing the "head" of a beef cysticercus, magnified thirty-five 

 diameters. Suckers have been mistaken at various times for eyes, for nostrils, and for 

 mouths, with none of which organs are the parasites provided. In live specimens the 

 suckers are frequently seen to protrude and retract. They are used by the worms for 

 attaching themselves to the intestinal walls, when they get transferred thither. A 

 fifth sucker may nearly always be detected in this species, although the statement 

 has often been called into question, but this fact is indisputably proved by its 

 presence in the print of micro-photograph No. 9, in which the head of a beef cysticercus, 

 magnified thirty-five diameters, has been snipped off with a scissors and carefully 

 dissected, under water, on the stage of the microscope, so as to show the Hve suckers 



pjg. 30. Diagrammatic, showing the inverted and coiled condition of the '• head " and " neck " with 



the relation of the latter to the receptaculum. 



when spread out between a covering glass and slide. In the spot corresponding to 

 this central rudimentary sucker or surrounding it, a series of sharp pointed hooks 

 is developed in the pork variety, which constitute the essential difference between 

 these two species of bladder- worms. The relation of the hooks to the four suckers is well 

 shown in the micro-photograph (No. 10, Plate XXXVII), of the head of a pork bladder- 

 worm dissected and spread out as in the other species. The hooks are arranged in two 

 rows the inner row being the larger, twelve or thirteen, sometimes more in each row; 

 the points of both rows being directed forwards and outwards, so that this species is 

 thus enabled to take still firmer hold of its " host" than those found in beef and 

 veal. Micro-photograph No. 11 represents the ring of hooks in the dissected prepara- 

 tion more highly magnified than in No. 10 ; a one-inch objective being used in the 

 latter case and a quarter in the former. 



Excepting that the pork worm is provided with the hooks just described, and that 

 the beef worm presents a fifth or central sucker, there is no difference in the micro- 

 scopic appearance of the two varieties. In both the "head" and "neck," together 

 with the reflected portion of the latter, are thickly scattered with oval calcareous 



