Page:Encyclopædia Britannica, Ninth Edition, v. 19.djvu/878

Rh 854 PROTOZOA [SPOROZOA. protomerite) and a larger posterior (the dentomerite), 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 protomeritc. The epiinerite serves to attach the parasite to its host, and may for that purpose carry booklets. It is always shed sooner or later. The phase in which it is present is called a &quot; ct-phalont,&quot; the phase after it has broken off a &quot;sporont&quot; (see Fig. XIX. 22, 23). The spores are smaller than in the preceding group, often very minute, and some times the cyst is complicated by the formation of sporoducts, and by a kind of &quot;capillitium &quot; of residual protoplasm (Fig. XIX. 2). Spores producing each only a single (?) falciform young. Genera. Gregarina, Dufour ; Hoplorhynchus, Von Cams. [The numerous genera which have been proposed at different times by Hammerschmidt 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 less 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 that 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 the 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 booklets. The presence of booklets 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 Fig. XIX. for various examples of the group. 3 y of M&quot;&quot;** offitin, the common Gregarinide of the irthworm ; x 750 diani. ; showing ripe chlamydospores and complete fwMnal) *&quot;* r Ual I roto P lal *n or other material in the cyst SUB-CLASS II. Coccidiidea, Biitscbli (9). Sporozoa in which the euglena phase remains of relatively minute size, of spherical shape and simple egg-cell-like structure
 * is not locomotive, but continues, until the cyst is formed to

inhabit a single cell of the host. Many, few, or one single chlamy- lospore are formed in the cyst. One or more falciform young scape from each spore, and exhibit active movements (flagellula i) leading to a penetration of a tissue-cell by the youn&quot; form as in Greganmdea. .Many are parasites of Vertebrata. OUDER 1. MONOSPOREA, Aim. Srlrn. Character*. The whole content of the cyst forms but a single spore. Genus unicum. Elmer ia (in the intestinal epithelium of Triton Lithobius an(1 SV VW, 1 FIG. XIX. Sporozoa (Septata). 1. Gregarina blattarum, Siebold, from the intestine of Blatta orientalig; 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 which is the nucleus a. 2. Over-ripe cyst of Gregarina blattarum, with thick gelatinous envelope e, and projecting sporoducts d. The spores have been nearly all discharged, but amass 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- everted sporoducts ; e, the gelatinous envelope. 3. A ripe spore (chlamydo spore) of Gregarina blattarum, a long time after its escape from the cyst ; x 1600 diam. 4. Commencing encystment of a syzy- gium of G. blattannn. a, protomerite of one individual ; b, gelatinous envelope ; c, protomerite of the second individual. 5. Three epithelial cells of the mid-gut of lilatta oiimtalia, 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 &quot;cephalont&quot; ; it will then become a &quot;sporont.&quot; 7. Basal part of an everted sporoduct of 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.