KUNGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 63. N:0 9. 11 



at the end of August have also been studied with the following result: In all the zooids 

 examined the testes were highly reduced in size as compared with the above stages. 

 In some there was hardly any trace of them, in others a small remainder was found 

 on one side or on both sides; in a few individuals the testes were easily distinguishable 

 though the lobes were thin and flattened. No large eggs nor any embryos were 

 observed in the female organs. Thus a reduction seems to take place at the end of 

 the season of sexual maturity in both the male and the female organs. 



When we consider what has been mentioned above as to the development of 

 the reproductive apparatus, it seems most probable that the male and the female 

 organs which occur at the same time in the very young bud and which are found fully 

 developed at the same time in full-grown individuals, are also reduced at about the 

 same time, viz. at the end of the season of sexual maturity. It seems possible too, 

 that the testes or traces of the testes may persist, in some individuals at least, longer 

 than traces of the female apparatus, though it is rather difficult, as far as I can see, 

 to decide when or whether the small ova are entirely reduced. But the latter 

 circumstance can hardly be considered as an evidence of the existence of a unisexual 

 state in the sense implied by previous authors; Michaelsen for instance states 

 that »Die Personen des B. leachi sind — — — vielleicht zum Teil eingeschlechtlich 

 männlich». The existence of such a state appears to be only hypothetical on the 

 following grounds: 



In some individuals in colonies collected off the Swedish coast in July, i. e. 

 during the actual season of sexual maturity, well-developed testes were found though 

 no female organs were distinguishable. But in such cases the supposition seems to 

 suggest itself that they represent zooids that have j ust been deli vered of their larvse. Some- 

 times female organs are wanting on the one side only though testes are present on 

 both sides, which may be due to the embryos having passed out into the outer 

 world at different stages. 



Immature eggs have often been observed at the posterior börder of the testis, 

 in the vicinity of the former place of the female apparatus; whether they are homo- 

 logous with the ova already developed is not, hovvever, certain, though their position 

 seems to favour such a supposition. 



It would appear from a study of sections made that there are small eggs to 

 be found diffusely spread about in the mesoderm of the full-grown zooids. The relation 

 of those eggs to the ovaries described as occurring in the very young bud has not 

 as yet been made out, and we know nothing for certain as yet as to their origin 

 and further development. Before those peculiarities of the female organs have been 

 investigated and fully explained, it is not possible, as far as I can see, to state 

 anything about the existence of unisexual male individuals in the Botryllidoe. 



It may be added that the reproduction by budding has been observed in all the 

 stages investigated with the exception of stage I. It commences very early in young 

 buds and probably goes on during a great part of the life-time of the zooid. 



