. A manual of zoology. Zoology. 2S2 CCELHELMIXTHES A third character is the marked dorsoventral flattening of the body (except in Ichthyobdellid;e and a few other forms), tlie animals thus re- calling lire Ihitworms. Tliis may be the result of llie very slight develop- ment of the ctTelom. In most leeches there is a body parenchyma, traversed bv muscles in which the organs are immediately im- bedded (fig. 20g). The alimentary tract bears paired diverticula (lig. 270), varying in number in different species. Between the last and largest pair of tliese is the intestine, wliich opens dorsal to th
. A manual of zoology. Zoology. 2S2 CCELHELMIXTHES A third character is the marked dorsoventral flattening of the body (except in Ichthyobdellid;e and a few other forms), tlie animals thus re- calling lire Ihitworms. Tliis may be the result of llie very slight develop- ment of the ctTelom. In most leeches there is a body parenchyma, traversed bv muscles in which the organs are immediately im- bedded (fig. 20g). The alimentary tract bears paired diverticula (lig. 270), varying in number in different species. Between the last and largest pair of tliese is the intestine, wliich opens dorsal to the posterior sucker. The jawed and jawless leeches show considerable differences in the pharvngeal region. In the first tliere are three semi- circular jaws in the pharynx, the free edge of each armed with teeth (fig. 271). To these are attached two muscles, one to retract tliem, while tlie otlier exserts and . -3^] rotates them, causing a trirachate wound from which the blood Hows. Tills bleeding is difficult to staunch, since a secretion of glands on the lips and between tlie jaws W Mc. ^^ Q a vr 711 Fig. ;6q. Fig. 26q.âTransverse section of Hinido ivcJiiliialis (from ;' dorsoventral, longitudinal, anil cirular muscles; â :â /, rJ, ;â ;', lateral, dors blood-vessels, the latter surrounding the ventral nerve cord, hi; /j, testes; â ; vid, midgut; up, nephridial tubule; cnp, urinary bladder. Fig. 270.âDigestive tract of Ilirudo mcdicinalis (after Hatschek). and anus; />, last ca-cal jiouches of intestine; (/, intestine, opened at c/'; dg, lateral blood vessel; o, a-sophagus; sc, nejihridia. duj, hii, r;», .\m\ \entral as deferens; (7, reetuni (.lorsal, Ig^ liinders the coagulation of the blood. In the jawless k^eches a sharp conical process arising from the pharynx serves for wounding and sucking. The vascular system usually contains red blood, and consists, ill the Gnathobdellid;e, of four longitudinal trunks, a dorsal, two lateral,. Please note that these imag
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectzoology, bookyear1912
