36 SIDNEY F. HAUMEB. 



new colonies.^ It should be further noted that the production 

 of new polypides in old zooecia is one of the most characteristic 

 ways in which the property of budding manifests itself in 

 Ectoprocta, and that this process is most easily interpreted as 

 a process of regeneration of lost parts. 



The provisional conclusion may therefore be stated as 

 follows : — That the process of embryonic fission, which may 

 appear abnormally in certain individuals in so many groups of 

 animals which do not multiply by fission, has in Crisia become 

 a normal phenomenon of the development ; and that this pro- 

 cess is correlated with the tendency which is so strongly 

 marked in the Polyzoa to produce buds in the adult condition. 



Giard (11) has recently published a note on what he terms 

 " poecilogonie," i. e. the phenomenon exhibited by certain ani- 

 mals of developing in a raoi'e or less ''condensed" manner, in 

 correlation with the amount of nutritive reserves in the egg, 

 or with the conditions under which the parent is living. As 

 examples of this process are mentioned, inter alia, the follow- 

 ing cases : — In Leptoclinum lacazii, Gd., the same colony 

 may produce two sorts of eggs ; of these, one is poor in yolk, 

 and gives rise to small larvae, whose tail is absorbed early, and 

 which do not begin to bud even on the third day. The other 

 kind is rich in yolk, and produces larvae which are still free- 

 swimming on the fourth day, and which then already contain 

 a colony of three individuals. Ophiothrix fragilis, Miill., 

 lays eggs which develop, according to the conditions, either 

 into perfect or into imperfect Plutei, or into embryos incapable 

 of swimming, and which develop directly. The remarkable 

 variations in the development of Aurelia aurita and of 

 Palsemonetes varians are also included in this category; in 

 the latter form the size and number of the eggs, as well as the 

 rapidity of the metamorphoses, varying according as the animal 

 lives in the brackish waters of the North or in the fresh-water 

 lakes of the South. 



Giard's observations suggest that the acquirement of em- 



' The statoblasts of the Phylactoleemata are indeed a further exception, 

 since each of these bodies is able to give rise to a new colony. 



