70 PEACTICAL PARASITOLOGY 



to it should be removed, and the intestine (which is so long that a 

 fourth part will be sufficient for demonstration purposes) teazed out 

 in normal saline solution. The parasites will remain alive for a 

 slightly longer time (two to three hours) if, instead of normal saline, 

 the contents of the gut are diluted with the body secretion of the dead 

 Lithobius, this generally sufficing for one preparation. 



If the centipede is infected, all the developmental stages charac- 

 teristic of the Coccidia will be found in the gut. The asexual repro- 

 ductive forms should be noted, as also the characteristic movements 

 of the young forms or merozoites. These movements are : (1) Gliding 

 movements, by which the merozoites move forward without any 

 visible change of form and with their more pointed end in front. As 

 in the Gregarines, a jelly-like peduncle is formed, which may be seen 

 if a small quantity of sepia is added to the preparation. (2) Bending 

 and stretching movements, which alternate with great regularity, the 

 merozoite slowly doubling together and then stretching itself out with 

 a jerk. (3) Contractions, in which a ring-shaped constriction, com- 

 mencing close behind the hyaline anterior tip, travels slowly as a 

 continuous wave of contraction along the entire length of the body. 



The living parasite should be studied with an oil-immersion lens, 

 when the alveolate structure of the protoplasm will become clearly 

 visible. If this is seen in the stained and coloured specimen only, it 

 may be mistaken for an artificial effect. 



The merozoites differ from the sporozoites, which they otherwise 

 closely resemble, in the possession of a nuclear caryosome. This 

 caryosome is absent in all the stages of sporogony, as it becomes 

 destroyed in the process of nuclear reduction which precedes fertiliza- 

 tion. It does not again make its appearance until the sporozoites 

 change into schizonts. 



In addition to schizonts, sex-forms will be found where the infec- 

 tion is not very recent. Under such conditions, if sufficient time is 

 devoted to the study of the individual stages, it is sometimes possible 

 to watch the maturation of the gametes and their fertilization under 

 the microscope. The macrogametocytes and the macrogametes be- 

 come differentiated from the schizonts by the accumulation in the 

 plasma of granular reserve material of a high refractivity. The micro- 

 gametes, on the other hand, are easily recognized by their clear, close, 

 small-meshed protoplasm. 



The identification of the different developmental stages is rendered 

 difficult by the fact that three varieties of Coccides are found in the 

 centipede, and they may all be present iri a single host at one and the 

 same time. Of these three varieties, one only, Adelea ovata, undergoes 

 sporogony in the intestine of its host, where oocysts in all stages of 

 development may be found. They are oval in shape and develop 



