36 



PROF. AGASSIZ S 



body; but this form resembles so much that of the 

 suckers, that they must be considered simply as a 

 modification of them 



And if the suckers are buds, these must be closed 

 buds. Then there are still other buds, which re- 

 main closed, and which gradually swell and sink. 

 They do not assume so much individuality as to 

 open outside, arid to peform other functions. Ad- 

 mitting simply the fluid within, and pushing it out 

 again into the common cavity. 



Such buds are imperfectly developed individ- 

 uals, performing the function of respiration. 



They are individuals to breathe, as there are in- 

 dividuals to seize the prey; as there are individuals 

 to digest, living upon one common stock. There 

 are other individuals which bud also, and they are 

 ovaries. Here, Fig. XXVI, apparently an organ, 

 but nevertheless, arising like the other buds re- 

 productive individuals, and of these there are 

 even two kinds such as assume the form of 

 bunches of grape?, and others which assume the 

 form of those small Medusas here, (of Plate XX. 

 Fig. B) and which occur, especially in the lower 

 portion of the animal swim away freely, and re- 

 produce free individuals. 



Now if it was not for these cases such buds 

 which may reproduce the whole colony such a 

 conclusion as I am about to present would seem 

 untrue. But, when there are some among these 

 various buds which actually present the structure 

 of medusae, we must conclude that the s -called 



Physophoridse are compound animals, in which 

 the various functions of the body of medusae are 

 distributed to different individuals in a most diver- 

 sified manner, they being, however, not organs of 

 one animal, but of a community of individuals.each 

 performing special functions ; the whole exempli- 

 fying what a well regulated Society should be. 



There is the most remarkable resemblance be- 

 tween, the mode of association of individuals in the 

 compound animals which throw out buds, connec- 

 ted with the primitive stock, and the plants which 

 produce successively buds of different kinds. In- 

 deed the branching of trees from buds compares in 

 all its features with the budding of compound ani- 

 mals, and the similarity is closer in proportion as 

 there are more buds of different kinds produced, 

 which through life are confined to particular pur- 

 poses ; for instance, plants which produce similar 

 buds, growing into branches, identical with the 

 main stalk, will compare with the simpler forms of 

 compound animals, in which all the buds produce 

 individuals similar to the primitive stem. Plants, 

 on the contrary, which produce at various periods 

 leafy buds, and flowering buds, in which the male 

 and female flowers may even be separated, will 

 compare more closely with compound animals, 

 consisting of heterogenous buds which remain gen- 

 erally united for life, and from which only from 

 time to time eggs, or peculiar buds, are detached, 

 like seeds, to produce new individuals and new 

 communities. 



LECTURE V. 



After illustrating the structure and embryonic 

 development of the Jelly-fishes, I did not draw 

 any conclusion in my last lecture as to the natural 

 classification of these animals ; because I wanted 

 first to examine more closely the class of Polypi, 

 in order to trace, if possible, defined limits between 

 these two classes. Indeed, there is great difficulty in 

 ascertaining the proper limits of the class of Poly- 

 pi as a natural division of the animal kingdom, 

 owing to their low position in the series. Their 

 structure is so simple, that they are apparently re- 

 lated to all the lower types of other divisions. And 

 indeed we find that animals of very different types 

 have been referred to the class of Polypi. TheVe 

 have been articulated animals brought in connec- 



tion with them. There have been Mollusca re- 

 ferred to that group. And even at the present 

 moment, after anatomical investigations have 

 thrown so much light upon this subject, I incline 

 to admit that the class of Polypi, as it is now cir- 

 cumscribed, is by no means a natural one ; and in- 

 tend this evening to show that entire groups, con- 

 sidered by all naturalists at the present moment as 

 Polypi, will have to be removed from that class, 

 and that other types, which are referred to other 

 classes, will have to be combined with this class. 

 It will be perhaps best to begin this illustration by 

 pointing out the various forms which are thus 

 combined at the present moment as one class, un- 

 der the name of Polypi. 



