KUNGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 63- N:0 9. 7 



on the one side only. The eggs lie in the mesoderm isolated from each other, they 

 are not enclosed nor produced in a gland as is the case in higher Ascidians. Conse- 

 quently the female organ of this Botryllid species is not represented by an ovary 

 in the proper sense of the word. The ovary or group of eggs representing it, has, 

 like other ovaries, a constant position, always occupying the same place in the 

 posterior part of the body behind the male glands, i. e. it is always to be found 

 in the vicinity of the posterior end of the peribranchial cavity which here shows a 

 peculiar differentiation. 



As appears from fig. 1, the large eggs each show a small protuberance projecting 

 towards, and in close contact with, the peribranchial wall, or rather with a diverticulum 

 of it, represented by a small globular vesicle with a constricted neck. The bottom 

 of the vesicle-like pouch is concave, owing to the pressure of the above-mentioned 

 protuberance of the egg. In the following pages it will be shown by sections that 

 the vesicle-like pouch is the rudiment of a brood-pouch, and the protuberance 

 from the egg is a structure analogous to an oviduct. 



In this individual buds are observed growing out of the bod3 7 -wall in the 

 vicinity of the reproductive organs, often on a level with the anterior end of the 

 testis. The faculty of budding is thus manifested in verv young stages of the 

 individual development. 



Stage III (Pl. 1, fig. 2. Text-fig. 2). In a zooid measuring about 2 mm. 

 in length the reproductive organs are fully developed. As may be seen from the 

 figure illustrating this stage, the testes are larger than in stage II, while the lobes 

 are well distended and of larger size. The lobes are also more numerous, there being 

 about six of them. Sections made through them show that they contain fully developed 

 spermatozoa. Even mature eggs occur in this zooid, as will be evident from what follows. 

 Thus in the same individual both spermatozoa and ova are found mature together. 



As to the female organs we recognize the same structures as in the above 

 stage, though they are further developed. — It may be observed that the figures on 

 the plate are all drawn on the same scale. — One mature egg is to be found on each 

 side, occupying the same position as in stage II. There are small eggs too, though 

 they are not visible in the figure, being situated behind the large eggs. The small 

 protuberances, i. e. the oviducts spöken of above, are easily 

 distinguished; owing to their pressure, they give a bell- 

 shaped form to the vesicle-like rudimentary brood-pouch, 

 which covers the egg with so to say a vaulted roof. 

 The connection between the brood-pouch and the peribran- 

 chial sac is most distinctly shown in the figure, and the 

 development of the brood-pouch as a direct projection out 

 of the peribranchial cavity is indisputable. 



Text-fig. 2 represents a section made through the Text _ fig . 2 . M etrocarpa i mcM Savigny 

 female reproductive apparatus of an individual in this n - s en - Section through the female 



1 * L m organs. XI 10. öp. Brood-pouch. te. 



stage. The brood-pouch is cut obliquely ; it is a wide pouch Ectoderm. /. Outer foliicie. o. Ovum. 



r iic ,, i j j " r -i i • i od- Oviduct. p. Outer wall of the 



ot rounded torm, the concave bottom oi it being shown peribranchial cavity. t. Testis. 



