PROTOZOA 



25 



protomente) and a larger posterior (the deutomerite), in which lies 

 the nucleus. There is frequently if not always present, either in 

 early growth or more persistently, an anterior proboscis-like appen- 

 dage (the epimerite) growing from the protomerite. The epimerite 

 serves to attach the parasite to its host, and may for that purpose 

 carry hooklets. It is always shed sooner or later. The phase in 

 which it is present is called a " cephalont," the phase after it has 

 broken off a "sporont" (see Fig. XIX. 22, 2-3). The spores are 

 smaller than in the preceding group, often very minute, and some- 

 times the cyst is complicated by the formation of spovoduots, and 

 by a kind of " capillitium " of residual protoplasm (Fig. XIX. 2). 

 Spores producing each only a single (?) falciform young. 

 . Genera. —Qregarina, Dufour ; lloplorhynchus, Von Carus. 

 ._ [The numerous genera which have been proposed at different 

 times by Hammersohmidt and others, and more recently by Aime 

 Schneider, appear to the present writer to be unserviceable, owing 

 to the fact that our knowledge is as yet very incomplete. A 

 good basis for generic or family distinctions might probably be 

 found in the greater or loss elaboration of the cyst and the forma- 

 tion or not of sporoducts.' But of the majority of Septata we do 

 not know the cysts or the history of sporulation ; we merely know 

 tha,t some have simple cysts with complete sporulation leaving no 

 residue of protoplasm, and that others form cysts with double walls 

 and elaborate tubular ducts, whilst a part of the protoplasm is not 

 sporulated but forms a capillitium (Fig. XIX. 2). 



Another possible basis for generic division of the Septata may 

 be found in the characters of thel epimerite. This may be present 

 or absent altogether. It may exist only in the young condition or 

 persist until growth is completed. It may be simple, short, 

 elongate, or provided with hooklets. The presence of hooklets on 

 the epimerite is the only character which at present seems to serve 

 conveniently for generic distinction. "With regard to the other 

 points mentioned we are not sufficiently informed, since we know 

 the complete history of development from the young form set free 

 from the spore in only one or two cases. ] 



The Septata are found exclusively in the alimentary canals of 

 Arthropoda (Insects, Myriapods, -Crustacea, not Arachnida). See 

 Kg. XIX. for various examples of the group. 



FIO. XVIII. — Cyst ot Morweystis agUis, the common Gregarinlde of the 

 Earthworm ; X 750 diam. ; showing ripe chlamydospores and complete 

 absence of any residual protoplasm or other material in the cyst 

 (original). 



SuB-OLAss II. Coocidiidea, Biitschli (9). 



Sporozoa in which the euglena phase remains of relatively 

 minute size, of spherical shape and simple egg-cell-like structure. 

 It is not locomotive, but continues, until the cyst is formed, to 

 inhabit a single cell of the host. Many, few, or one single chlamy- 

 dospore are formed in the cyst. One or more falciform young 

 escape from each spore, and exhibit active movements (flagellula- 

 like) leading to a penetration of a tissue-cell by the young form as 

 in Gregarinidea. Many are parasites of Vertebrata. 



Okdee 1. MONOSPOREA, Aim. Schn. 



Characters.— 'She, whole content of the cyst forms but a single 

 spore. 



Genus unicum. — Eimeria (in the intestinal epithelium of Triton, 

 Frog, Sparrow, Mouse, and the Myriapods Lithobius and Glomeris, 

 Fig. XVII. 35 to 39). 



ria. XIX. — Sporozoa (Septata). 1. Gregarina Uattarum, Siebold, from 

 the intestine of Blaita orientalis ; X 80. A syzygium of two individuals. 

 Each animal consists of a small anterior chamber, the protomerite, and a 

 large posterior chamber, the deutomerite, in whicli is the nucleus a. 2. 

 Over-ripe cyst of Gregarina blattaruTn, with thick gelatinous envelope e, 

 and projecting sporoducts d. The spores have been nearly all discharged, 

 but a mass of them still lies in the centre of the cyst 6. The specimen has 

 been treated with dilute KHO, and the granular contents of the cyst 

 dissolved. Around the central mass of spores is rendered visible the net- 

 work of protoplasmic origin in which the ejected spores were embedded. 

 This distinctly resembles in origin and function the capillitium of, 

 Mycetozoa (Fig. III.), a, the plasmatic channels leading to the everted 

 sporoducts ; b, the still remaining spores ; c, the proper cyst-wall ; d, the 

 everted sporoducts ; «, the gelatinous envelope. 3. A ripe spore 



(chlamydo spore) of Gregarina blatfarwm, a long time after its escape 

 from the cyst ; x 1600 diam. 4. Commencing encystment of a S3'zy- 



gium of G. blattarum. a, protomerite of one individual ; b, gelatinous 

 envelope ; o, protomerite of the second individual. 5. Three epithelial 



cells of the mid-gut of Blatta orientalis, into the end of each of which an 

 extremely young Gregarina blattarum has made its way. 6. Further 



development of the young Gregarina ; only the epimerite a is now buried 

 in the substance of the epithelial cell, and this will soon break off and set the 

 Gregarina free. It is now a "cephalont"; it will then become a "sporont." 

 7. Basal part ot an everted sporoduct ot Gregarina blattarum. a, granu- 

 lar-fibrous mass investing the base of the duct; b, commencement of the 

 plasmatic channel in the interior of which the sporoduct was produced as 

 an invaginated cuticular formation before its eversion. 8. Gregarina 



gigantea, E. Van Ben., from the intestine of the Lobster ; X 150. a, nucleus, 



D 



