30 INFUSORIA AND RIIIZOPODA. <§> 17. 



These movements succeed each other at more or k^ss regular intervals. 

 When these cavities are numerous, a certain order in the succession and 

 alternation of their contractions cannot always be observed. It is very 

 probable that their liquid contained during the diastole is only the nutri- 

 tive fluid of the parenchyma, and to which it returns during the systole. 

 In this way it has a constant renewal, and all staguatiou is prevented. 

 This arrangement constitutes the first appearance of a circulatory systejn, 

 and the first attempt at a circulation of nutritive fiuids. 



From an optical illusion simihir to the one mentioned as belonging to 

 the vacuolar C^ 13) the liquid of these pulsating cavities has a reddish hue.*" 



§ 17. 



A round, pulsating cavity is found in the genera Vorticella, Epistijlis, 

 Loxodes, and in the following species: — Amoeba diffluens, Paj-avmcium 

 kolpoda, Slylonychia mytilus, Euplotes patella, SfC. With Actinophrys, 

 Bursaria, Trichodi?ia, there are from one to two ; with Arcella vulgaris, 

 three to four ; with Nassula elegants, there are four placed in a longitudinal 

 line on the dorsal surftice. With Trachelius meleagris, there is a series 

 of eight to twelve upon the sides of the body, and with the various species 

 of Amphilej)tus there are fifteen to sixteen arranged more or less regularly. 

 With Stentor, there is a large cavity in the anterior portion of the body, 

 and many similar cavities appear upon the sides, united sometimes into 

 one long canal. A similar canal traverses the entire body of Spirostomum 

 ainhiguum, and Opalina planariarum. With Paramcecium aurelia, the two 

 round cavities present a remarkable aspect, being surrounded by five or 

 seven others, small and pyriform, the top of which being directed outward, 

 the whole has a star-like appearance.'^' During the pulsation, often the 

 entire star disappears, sometimes only the two central cavities, and in some 

 cases the rays only. 



These cavities, entirely disappearing in the systole, reappear in the dias- 

 tole, and usually in the same place and with the same form and number. 

 This would lead us to conclude that they are not simple excavations in 

 parenchyma, but real vesicles or vessels, the walls of which are so excess- 

 ively thin as to elude the highest microscopic power. 



In some individuals, as, for instance, with Trachelius lamella, there 

 appear, during the diastole, two or three small vesicles at the extremity of 

 the body, which, after having increased in size, blend into one which is 

 very large. These are probably only globules of nutritive fluid, separated 

 from the parenchyma. Similar phenomena are observed in Phialina ver- 

 micularis and Bursaria cordiformis. 



It sometimes happens with these animals that a forcible contraction of 

 the whole body divides an elongated cavity into two spherical portions, as 



i Ehrenben: (loc. "cit. p. 321, Taf. XXXIII. fijr. in the body. It really seems very strange that 



viii.), deceived by this illusion, has taken the eip:lit these animals should practise uninterruptedly these 



to twelve contractile cavities of Traclieliiis melea- pollutions throughout their entire life. These ani- 



^ris for stomachal cells, tilled with red gastric juice, mals have neither testicles nor ovaries, and the 



He has also regarded these cavities, when simple or function of these cavities is not, therefore, that 



double, as seminal vesicles. (Abhandl. d. Berliner assigned to them hy Elir enben^, — hnt is, as I 



Akad. 1833, p. 17'2, — 1S35 p. 158.) In species think, wUh jyiesmann (Arch. f. Naturg. 1835, I. 



having but few, he has very arbitrarily decided that p. 12), analogous to that of a heart, 



some are seminal vesicles, others stomachal pouches, ^ Dujardin, Ann. d. Sc. Nat. Zool. tome X. PI. 



as, for example, in Amphikptus (loc. cit. p. 355). XV. fig. 3 ; also, " Infusoires," PI. VIII. tig. 6. 



According to him, the seminal vesicles, upon con- Ehrenberg''s plates of these star-like vesicles are 



traction, pour the sperm upon the eggs contained incorrect. 



