KEPRODUCTIOX IN THE INFUSORIA. 183 



curious monstrosities ; a double ovary being associated with 

 a (or absent) testis, or vice versa. " It is an interesting 

 circumstance to note that all these abnormal individuals came 

 exclusively from media nearly putrid, which had become 

 transformed into genuine infusions, and were, consequently, 

 very rich in nutrient matters/'' The earliest Paramecium 

 aurelia has a very soft ovary, and a pale, rounded, inconspi- 

 cuous testis. Ill large specimens of Chilodon cucullulus, the 

 ovary (to whose simple structure reference has already lieen 

 made) attains a length of "032 mm., and a breadth of "021 

 mm., the mean diameter of the testis being "003 mm. The 

 following table exhibits, in fractions of a millimeter, the 

 average dimensions of these organs, in various other Infusoria 

 belonging to the same division ; 



2. The second arrangement holds good in the Euplotina, 

 Aspidiscida, and most Vorticellina ; also, in certain isolated 

 members of other families, as Trachelius ovum and Proroclon 

 niveum among the Trachelina, and, of the Bursarina, Bur- 

 saria truncatella. " In the two first groups the ovary is 

 almost always simply bent like a horse-shoe, and its con- 

 vexity looks sometimes to the left, as in Euplotes, or forwards, 

 as in Aspidisca. Among the Vorticellina this gland presents 

 the most numerous variations as to length, longitudinal or 

 transverse aspect in relation to the axis of the body, and the 

 number and direction of its curves. ^^ The male organ re- 

 sembles that of the preceding division, and is either free or 

 more or less united to the ovary. In Euplotes it is usually 

 placed on the left margin of the latter, in the anterior half 

 of the body. In Cothiirina imberbis it is sometimes situate 

 towards the top of the ovary, sometimes against its side, or 

 it may be received into a depression of its surface. 



3. In the last division are placed Oxyiricha and its imme- 

 diate allies [Stylonychia, Kerona, Urostyla, &c.) together 

 with various other forms of widely different affinities, as 

 Stentor, Kondylostoma, and some species of Amphileptus and 

 Loxophyllum. 



The Oxytrichina proper have both ovary and testis divided, 



