524 



TELOSPORIDIA 



multiplies by binary division. After some time it takes on a greg^ariniform 

 phase, and becomes attracted to an epithelial cell in the stomach of the 

 mosquito by its fiagellum, which is reduced to a short rod. While so attached 

 it may multiply by binary division, and may also penetrate in between the 

 cells of the stomach and encyst, losing its fiagellum. 



After a period of rest the trypanosome can become active again, but after 

 a time it must either (i) pass into the blood of the little owl; (2) become a 

 male or female form; (3) die out. 



The Male Ookinete. — The male ookinete forms a heteropolar diaster, but 

 with a subdivision of the elements into male and female instead of into kinetic 

 and trophic. 



The larger or female portion disappears, while the smaller or male portion 

 forms eight double nuclei, with kinetic and trophic elements, which are dis- 

 tributed throughout the cytoplasm. 



The ookinete now becomes rounded, while the eight double nuclei travel 

 to the periphery, which grows out into little elevations, each with a double 

 nucleus. Each little elevation grows into a little male trypanosome in the 

 same manner as in the indifferent form, and breaks off from the ' rest body ' 

 [nucleus de reliquat) of the parent cell. These male trypanosomes, according 

 to Schaudinn, simply die off. 



The Female Ookinete. — In this form the same changes take place as in the 

 male ookinete, but it is the small male nucleus which degenerates, after divid- 

 ing into a number of forms, while the large female nucleus, which consists 

 of the trophic and kinetic elements, remains, and forms a trypanosome in the 

 same manner as in the indifferent form. 



The female trypanosome is slow moving, and does not divide, but can 

 become gregariniform, and lie quiescent between the epithelial cells for a 

 time. It can also pass into the ovaries and eggs, and lie dormant during the 

 winter. 



The female ookinete, however, undergoes parthenogenesis by losing its 

 flagellar apparatus and developing a trophonucleus with a kinetonucleus in 

 contact with it. The kinetonucleus now divides, and undergoes reduction, 

 while the trophonucleus also divides, one portion being lost. The reduced 

 kinetonucleus, which has divided into two, now enters the trophonucleus from 

 opposite sides, and fusing, forms the synkaryon of an ookinete, which may 

 become an indifferent, a male, or a female trypanosome. 



In the Owl. — The male, female, and indifferent trypanosomes may be 

 injected into the owl during the process of biting by the mosquito, but the 

 majority are of the indifferent type. The male trypanosomes, if they enter, 

 die off. The indifferent trypanosomes divide in the blood until a small size 

 is reached, when they enter the erythrocytes, and become a young halter- 

 idium by the flagellar apparatus disappearing and the kinetonucleus approach- 

 ing the trophonucleus. 



In twenty-four hours this parasite, which now contains haemozoin, becomes 

 active, and, re-forming its flagellar apparatus, leaves the blood cell usually at 

 night as a typical Trypanosoma noctuce. After a short period of activity it 

 enters another erythrocytic, and grows till the next night, when it again 

 becomes free. This process takes place six times before the trypanosome 

 attains its full size, when it undergoes repeated division until again small, 

 thus completing the cycle of schizogony. The small extracellular forms may 

 be looked upon as the merozoites, and the intracellular forms as trophozoites, 

 and the large extracellular form as a schizont. The sexual forms are developed 

 from the merozoites — i.e., the very young indifferent trypanosomes — which 

 enter the red cells, and become microgametocytes and macrogametocytes, thus 

 completing the cycle of sporogony. 



Remarks. — Novy and many others are convinced that Schaudinn is entirely 

 wrong, and that he was dealing With a double infection of a halteridium and a 

 trypanosome, both of which probably develop in entirely different ways. We 

 are also convinced that these parasites are Hsemosporidia. 



