182 BALBIANI, ON SEXUAL 



striation of the gland than that which results from the rod- 

 like organs in question. 



Modifications of Ovary and Testis. 



The most striking diversities of form which both kinds of 

 reproductive bodies present have next to be considered. In 

 accordance with these modifications, the numerous species of 

 the class have been arranged by M, Balbiani, under three 

 principal divisions, as follows : 



1. — "Species whose ovary has the form of a small rounded 

 or ovoid cell, containing an undivided yolk-mass. Testis 

 (where it exists) presenting a like aspect. ^^ 

 2. — " Species having the ovary elongate, cylindrical and 

 tubular, variously curved or twisted, containing an un- 

 divided yolk-mass. Testis, as in the preceding species.^^ 

 3. — " Species having the ovary elongate, straight or curved, 

 containing a yolk-mass divided into two or more distinct 

 parts (bi- or multi-locular ovary). Testis usually made 

 up of an equal number of elements, accompanying the 

 yolk segments. More rarely a single male element." 

 These characters are more briefly exhibited in the subjoined 

 table : 



Yolk-mass, continuous . / § — 1 Ovaiy ovoid or spheroid. 



Testis, single. 1 § — 2"| 



Yolk-mass, divided . p o [ Ovary elongate. 



Testis like ovary, being single. ^ J 



1. To the first division belong all the Paramecina proper 

 {Colpoda, Glaucoma, Paramecium, Cyclidium, Pleuronema), 

 with various species and genera referable to other families, 

 e. g., of Trachelina, Nassida, Chilodon, Holophrya, Enchelys, 

 Prorodon teres ; of Bursarina, Plagiotoma, Balantidium, 

 Leucophrys, Frontonia {Bursaria leucas, Ehr.), Ophryoglena 

 [B. flava, Ehr.), &c. 



In these Infusoria the reproductive system may be said to 

 occur under its least complex conditions. The simple rounded 

 ovary, completely filled by its yolk-mass, appears always 

 situate about the middle of the body, and lodged in a depres- 

 sion of its surface is the oblong or spheroidal testis, the length 

 of which is most frequently from one sixth to one eighth that 

 of the female organ. In Paramecium bursaria it is somewhat 

 larger, nearly equalling the ovary in size. The generative 

 apparatus for this species is liable, occasionally, to certain 



