^140. 



THE ROTATORIA. 



149 



CHAPTER IX, 



OKGANS OF GENERATION. 



§ 140. 



Although it is certain that the Rotatoria propagate only by genital 

 organs, yet the female organs only are yet well known. These consist of a 

 single or double ovarian tube of vai'iable length, situated upon the sides of 

 the intestinal canal at the posterior part of the cavity of the body, and 

 opening into the cloacal cavity through a short oviduct. These ovaries 

 never develop but a few eggs at a time. The mature eggs are always 

 oval and surrounded by a simple, solid, colorless envelope. They contain 

 a finely granular and usually colorless vitellus, in which there is a distinct 

 germinative vesicle. Many species are ovigerous, but a few only are vivi- 

 parous. '^' 



It would be naturally supposed that these animals, which have such dis- 

 tinct female organs, would have also those of the other sex. But as yet the 

 most minute researches have failed to detect them. It is therefore doubt- 

 ful whether these animals are hermaphrodites or of separate sexes.t '-' 



1 For the various forms of the ovaries see tlie 

 classical works of Elirenherg. With Philodina 

 roseola, Brachionux rubens, and Masligocerca 

 carinata, the vitellus of the eggs as well as the 

 parenchyma of the body is of a reddish color. 

 With those species which live in the tubes, the 

 eggs are usually deposited in the cavity of these 

 last. But with Triarthra, Polyarthra, and 

 lirachionus^ they remain glued to the cloacal 

 opi'ning. 



W itli P/i ilodin a, the young are often hatched 

 in the cavity of the parental body, and are, accord- 



ing to Ehrenberg (Die Infusionsthierchen p. 483), 

 always surrounded with an extensible membrane 

 of the ovary (uterus). But it has always appeared 

 to me that the mature eggs of the viviparous Phi- 

 Zodwoe, are detached from the ovaries and fall into 

 the cavity of the body, where afterwards the 

 hatched young move about. Perhaps oviducts are 

 here wanting and the young escape from their 

 parent through an orifice near the cloacal open- 

 ing.* 



'i Admitting that there are here male genital 

 organs, the respiratory tube upon the neck of 



* [ § 140, note 1.] The view here expressed that 

 the young of the viviparous Philodinae may find 

 their escape from the body of the parent through 

 an opening near the anus — the oviducts being 

 perhaps wanting — is probably correct, since, in the 

 viviparous Aphides, where the processes of repro- 

 duction occur likewise by a kind of gemmiparity, 

 there are, according to my observations, no ovi- 

 ducts proper, but the young, having fallen into the 

 abd<}minal cavity, thence escape through a Porus 

 genitalis situated near the anus. — Ed. 



t [End of § 140.] The discovery of distinct 

 males with the Rotatoria is due to Bright we/l 

 (Ann. Nat. Ilist. Sept. 184S) who has positively 

 determined it with Asplanchna. Here it is about 

 half the size of the female, being also of a different 

 form ; it is exceedingly transparent and easily eludes 

 observation. The testis appeared as a round ves- 

 sel situated at the bottom of the body on one side, 

 and filled with spermatic particles. This author 



thinks also that he observed a well-defined intro- 

 mittent organ connected with the testis, and a 

 passage for its extension from the body of the 

 animal. 



In verification of this observation it may be men- 

 tioned that Brightwell observed the actual coitus 

 between the sexes, and Gosse (loc. cit. p. 22) has 

 witnessed the development of the males frnm the 

 ovum. 



Huxley, on the other hand (Quat. Jour. Mic. 

 Sc. No. I. Oct. 1852, p. 1), has found with Lacin- 

 ularia no trace of a male individuiil, but in some 

 specimens he observed singular bodies which 

 answered precisely to h'o/liker's description of the 

 spermatic particles of Megafotrocha. lie says, 

 " They had a pyriform head about 1-1000 in. ia 

 diameter by which they were attached to the parietea 

 of the body, and an ai)i)endage four times as long 

 which underwent the most extraordinary contor- 

 tions, resembling however a vibrating mcmbr.one 



