1881.] oil the Onyln of Colonial Organisms. 509 



gation of protoplasmic units, some of which resemble Amoebo3 in 

 uaturo, whilst others resemble Chlamydomonads. The protoplasmic 

 imits of a sponge-colony are, as a rule, united together by a common 

 skeleton they have helped to elaborate. Each sponge grows from an 

 egg, the process of reproduction by "budding" being also represented 

 in the group. Two SpongiUoi, or common fresh-water sponges, will 

 unite if placed in contact, or may separate spontaneously. Tho 

 sponge arising from an egg, like a higher animal, thus exhibits seg- 

 mentation and segregation of its parts, and comes to retain this segre- 

 gate and colonial nature as a permanent feature of their race. 



The Hydrre of the fresh-water pools, lead us to a type of animals 

 nearly related to the sponges. Each is a tubular animal which may 

 be artificially divided, and which throws off gemmae or buds naturally. 

 Each Hydra-bud grows into the exact likeness of its parent, and 

 ultimately detaches itself from the parent body. 



The zoophytes are simply Hydrce which have budded, but whose 

 buds remain permanent to form a veritable tree, whose growth is ever 

 increasing, and through whose branches a continual store of nutri- 

 ment is continually circulating. Many zoophytes produce eggs which 

 simply and directly develop into the compound adults by budding. 

 Others develop eggs through the media of jelly-fish or medusoid- 

 buds, which break away from the parent tree and live an independent 

 existence in the sea. In some zoophytes there may be seven difl:erent 

 kinds of units in the colony, all referable, however, to one type. 



A Flustra, or " sea mat,'' grows upon shells and resembles a piece 

 of pale brown seaweed. Each organism is an animal colony, but its 

 units, which may number several thousands in one organism, are not 

 structurally connected together like those of the zoophytes, but are 

 contained each in a separate cell. 



The Tceniada or tapeworms consist each of a linear series of similar 

 "joints." Each "joint" is in reality comparable to the unit of 

 zoophyte or " sea mat," for it is essentially a distinct member of a 

 colony, and possesses a complete set of generative and other organs, 

 and is produced from the head and neck by budding. According 

 to Haeckel, starfishes and sea urchins are each compound or " colonial " 

 animals. Structurally, it is provable that each ray of a starfish 

 corresponds with worm-structure in broad details. The Nais and 

 other fresh-water worms produce young forms by a new head being 

 budded out amongst their joints. There is here seen a tendency to 

 become doubly " colonial " ; inasmuch as the single worm is tyi^cally 

 a " colonial " animal, and the new head-development causes this 

 compound body to detach a new colony. 



Amongst insects, the Aphides, or plant-lice, produce by veritable 

 " budding " new generations, and the queen bee does not fertilize 

 those eggs which are destined to become " drone " bees. Thus, the 

 homology of an egg with a " bud " appears demonstrable. 



It is the business of philosophy to correlate and arrange facts to 

 form a harmonious and scientific system. The philosophy of biology 



Vol. IX. (No. 73.) 2 n 



