$§ 15, 16. 



INFUSORIA AND RHIZOPODA. 



29 



§15. 



The round or elongated oval mouth of Infusoria varies as to its posi- 

 tion. Sometimes it is in front, sometimes behind ; and in some cases, near 

 the middle third of the body. Rarely naked,''' its borders are generally 

 ciliated,'-' and often its circumference is provided with a very remarkable 

 ciliary apparatus. By the,aid of this, these animals not only move about, 

 but when quiet produce vortical actions of the water, which are felt at 

 quite a distance ; and all minute particles within its reach are quickly 

 drawn towards its mouth, and then swallowed or rejected according to the 

 option of the individual.''^' 



It is rare that this oral aperture is provided with a dental apparatus.***' 

 The oral cavity, generally infundibuliform, extends into a longer or 

 shorter, straight or curved oesophagus, which is lined throughout by a very 

 delicate ciliated epithelium.'" 



The anus, situated usually upon the dorsal surface of the posterior por- 

 tion of the body, is sometimes, though rarely, indicated by a slight exter- 

 nal projection.'"' 



CHAPTERS VI. AND VII, 



CIRCULATORY AND RESPIRATORY SYSTEMS. 



§ 16. 



A vascular system entirely distinct by closed walls from the other 

 organs is not found in the Protozoa. Rut with very many (with all the 

 Stomatoda, without exception) there are contractile pulsatory cavities, the 

 form, number and arrangement of which is quite varied. • 



They are situated in the denser and outer layers of the parenchyma of 

 the body, and during the diastole they become swollen by a clear, trans- 

 parent, colorless liquid, which, during the systole, entirely disappears. 



1 Actinophrys. The mouth is naked also in the 

 genera Diffiugia and Arcella of the Rhizopoda.* 



• Bursaria, Paramecium, Urostyla and Sty- 

 lonychia. In Glaucoma scintillans tlie ciUated 

 crown of the mouth is replaced by a special semi- 

 lunar ciliated lobe. 



3 In Stentor, Vorticella, Epistylis and Trjcho- 

 dina, this apparatus is retractile, and produces in a 

 particular way the vortical actions. In Spirosto- 

 mum ambiguum, there is a long, narrow, ciliated 

 furrow, through which the food is conducted to the 

 mouth, situated at the posterior portion of the body. 



■4 Prorodon, Nassu/a, Chilodon and Chlamido- 

 don. Here the hair-like teeth are arranged in a 

 cylinder so as to resemble a weir. 



5 The cesophagus is short in Oxytricha, Sty- 

 lonychia, and Euplotes ; but is elongated or spi- 

 ral in Vorticella, Carckesium and Epistylis; 



* f § 15, note l-l Kolliker ( Siebold and Kolli- 

 Aer's Zeitsch. 1. 1849, p. 198) has given a long and 

 detailed description of Actinophrys sol. Accord- 

 ing to him, it is without mouth or stomach proper, 

 and internally is composed of a homogeneous sub- 



3^ 



while it is long and arcuate in Bursaria trunca- 

 tella and cordiformis. 



The undigested matters accumulate about the 

 anus, and when this opens are expelled from the 

 parenchyma with a certain force. 'VMth Tfasnula 

 elegans, the greater or less portions of the Oscil- 

 latoria gracillima {Kutzing) upon which it 

 feeds, and which are of a blue-green color, dis- 

 solve into granules of this color. Rut these, dur- 

 ing the process of digestion, gradually assume a 

 brown color, and form irregular masses in the pos- 

 terior portion of the body, and are from time to 

 time expelled as brown ffjsces. These green gran- 

 ules are not therefore eggs, as Eftrenberg (\oc. 

 cit. p. 339) has supposed. This Nassula when 

 young is perfectly colorless, with the exception of 

 a beautiful blue spot. 



stance. Yet this remarkable am'nial lives on other 

 Infusoria, Algae, &c., and avails itself of them by 

 seizing and afterwards invaginating them in its pa- 

 renchyma, until they finally are mcluded within its 

 interior. — Ed. 



