^'S^ Dr. A. Braun on the Vegetable Individual. 



fectly similar to those which occur in the vegetable kingdom. 

 In animals which go through an alternation of generation, the 

 individuals of the preparatory generations are non-sexual ; still 

 they may ncvertlicless have a determinate importance in relation 

 to the completion of the race which is to form their posterity. 

 When in fact the final generation does not consist of hermaphro- 

 dite individuals, as obtains, for instance, in the Tape-worm, 

 various alternations are conceivable : the final individuals of both 

 sexes can be nourished by the same nurse, and hence the sexual 

 division will first take place in the second, or generally speaking, 

 in the last generation; or, different nurses may nourish the 

 two sexes, so that a division of generation will occur even at 

 the degree of nurse-formation. If in the last case the nurses 

 are not single ones, but even then form per se a family stock, 

 then on the same stock we may either have male-bearing and 

 female-bearing nurses together, or these two kinds of nurses 

 may be divided among different stocks, according as the division 

 of generation occurs in a determinate later generation, or is 

 present already in the first. Although as yet the observations 

 of these relations by no means form an unbroken chain*, still 

 this much is certain, that in animals, in the same way as in 

 plants, both monoecious and dioecious forms occur ; and hence 

 there are families partly bisexual, partly unisexual. Coryna, 

 .Tubularice, Campanularice, and probably all Sertularice (hence, 

 doubtless, the greater part oi Hydroids), also Veretillum, Cyno- 

 morium, according to Steenstrup, Krohn, and other observers, 

 are dioecious, whether they form small simple stocks, as Coryne 

 ^squamata, or small ramified trees, as Syncoryna, Campanularia-f, 

 ,&c. On the other hand, the Siphonophora, according to Milne- 

 Ed war ds^s description of >S/e/?A«yiomm J (and judging from Sars' 

 description of Agalmopsis), are monoecious family stocks ; Hydrce 

 are also monoecious §. To enter any further into these relations 

 as they occur in the lower animals would lead us too far from 

 our subject; but it may be in place to give some details as to 



* Thus, e. g., as far as I know, it remains to be shown whether the 

 single nurses of MeduscB produce Medusce of both sexes, or, as is most 

 probable, only those of the same sex. In Aphis also this point still needs 

 to be more accurately determined. 



t Steenstrup, Hermaphr. pp. 66, 67, 72. 

 ^,^^A Ann. des Sc. Nat. 1841, p. 217- pi. 7-10. 



I The later investigations into the Siphonophora by Huxley, Edin. Phil. 

 Journ. 1852, Kolliker, Zeitschr. f. wiss. Zool. 1852, and Leuckart, Zool. 

 Untersuch. Heft 1, 1853, corroborate the monoecious relations of these won- 

 derful creatures as regards most of their genera, e. g. Agalma, Agalmopsis, 

 Stephanomia {Apolemia), Physophora, and the other closely related genera. 

 Busch's researches into the group of DiphyidcB have proved them to be 

 dioecious, and the same obtains in the related genus Epihulia. (Later 



