366 



TR YPA NO SOMIDm 



separate blepharoplast ; but there does not appear to be a splitting of the 

 flagellum; on the contrary, Miss Mackinnon beheves that the new fiagellum 

 grows out from one of the blepharoplasts, but for some time the two flagella 

 lie close together, and this may last until the new fiagellum has reached the 

 length of the old flagellum. It is in this stage that the deceptive appearances 

 of a biflagellate organism is produced. The kineto nucleus divides, and the 

 trophonucleus also divides amitotically, the karyosome dividing first; after 

 this the cytoplasm divides. Division takes place so rapidly that the organisms 

 become smaller and smaller, and, attaching themselves to the epithelium of 

 the hind-gut, encyst — ^.^?,,pass into the post- flagellate stage of aflagellar cysts 

 (3 to 4 by 3*5 to 2-5 jul), possessing tropho- and kineto-nuclei. These cysts 

 pass out in the faeces, and are accidentally ingested by the fly along with food. 



Hereditary Infection. — No sign of hereditary infection could be found, nor 

 of sexual reproduction. 



Other Observations. — Prowazek describes asexual reproduction by longi- 

 tudinal division, in which the trophonucleus divides first, then the kineto- 

 nucleus, and lastly the flagellum; while Patton fails to find the division of the 

 flagellum, and states that the second flagellum is developed as an outgrowth 

 from the kinetonucleus, Prowazek has seen sexual conjugation, which Patton 

 fails to find. Prowazek describes encystment, and considers that the infection 

 is carried by the faeces, with which latter statement Patton agrees, Prowazek 

 finds that the male and female parasites penetrate into the eggs of the fly, and 

 undergo therein an autogamy by etheogenesis, in which the kinetonucleus 

 carries out the development; by parthenogenesis, in which the trophonucleus 

 is active; and by an indifferent type, in which both nuclei participate. There 

 are, however, many transitional forms between these stages. Patton's 

 description of the life-cycle is quite different, and resembles that which he has 

 given for Crithidia gerridis {vide p, 367). He further supports this life-cycle 

 by his previous description of a Herpetomonas in Culex pipiens. 



Herpetomonas jaculum Leger, 1902. 



This parasite, which was found in the alimentary canal of Nepa cinerea by 

 Leger, has been studied in detail by Miss Porter. 



Morphology. — This Herpetomonas in the flagellate stage measures 13 to 33 

 in length by i to 4 ^ in breadth, and is surrounded by a clear, flexible ectoplasm 

 provided with myonemes, inside which is a granular endoplasm with granules 

 arranged in such a way as to suggest a cytopharynx. The trophonucleus is 

 oval, the kinetonucleus is fairly large, and chromidia are found widely separate 

 from one another. A blepharoplast lies close to the well-developed flagellum. 



Life-History. — The flagellate attaches itself to the wall of the gut or to debris, 

 and divides until small motionless forms result, which, shortening and encyst- 

 ing, form the ' post-flagellate stage.' It now escapes from its host as minute 

 cysts in the fasces, which are deposited on the leaves of water-plants. The 

 faeces are eaten by the young Nepa — i.e., there is contaminative or casual in- 

 fection, and now the ingested cysts, which are small oval bodies, with tropho- 

 and kineto-nuclei, form the preflagellate stage of the life-cycle, which passes 

 into the flagellate adult stage. 



Hereditary Infection. — In addition. Miss Porter has seen flagellate forms 

 pass through the wall of the gut near the ovaries, into which they penetrate 

 and encyst, all of which is suggestive of hereditary infection. 



H. bUtschlii Saville Kent, 1881. 

 In Trilohius gracilis, but it has not been perfectly studied . 



H. pycnosomse Roubaud, 1904. 

 In Pycnosoma putorium Wiedmann, in Africa. 



H. davidi Lafont, 1909. 



Described in Euphorbia pilulifera by Lafont, in Mauritius, Ceylon, and 

 R6union, East and West Africa, West Indies, Portugal, and India. We have 



