168 SCIENCE PROGRESS. 



the colony, Mr. Harmer found that certain buds may be 

 distinguished at an early stage from the ordinary buds 

 which form the polypides of the Zocecia, by the fact that 

 each of them contains a single large cell or ovum. These 

 buds, separated off from the true growing point by ordinary 

 septa, and homologous with the Zocecia, become modified 

 to form the structures which are, rather unfortunately, 

 called the ovicells. Each " ovicell " is, in fact, a chamber, 

 in protoplasmic communication with its neighbours, largely 

 filled up with ordinary funicular tissue, but containing an 

 obvious polypide bud and one ovum. The process of fer- 

 tilisation was not observed, but there can be little doubt that 

 it takes place. The segmentation is remarkable for the fact 

 that the blastomeres are either very loosely connected with 

 one another or quite separate, a condition which is only 

 paralleled by the cases of Salpa, as described by Salensky, 

 and Dendroccelum, as described by Halley. This is followed 

 by the formation of an embryo, in which it is difficult to 

 distinguish any definite embryonic layers, as it consists of 

 simply an undifferentiated protoplasmic mass in which nuclei 

 are irregularly scattered. After a time this embryo sends 

 out several finger-shaped processes, each of which becomes 

 divided up into rounded masses of cells by a series of 

 transverse constrictions, and each of these rounded masses 

 of cells becomes a larva. 



Although this interesting process of embryonic fission 

 has only been observed in this one case of Crisia ramosa, 

 it is not improbable that future investigation will prove 

 that it is of common occurrence among the Cyclostomatous 

 Polyzoa. 



Among the notable papers of recent times, one by 

 Dr. Fowler 1 on the anatomy of Rhabdopleura must be 

 referred to. A renewed investigation of this interesting 

 form has led the author to the conclusion that it must be 

 included with Balanoglossus and Cephalodiscus in the group 

 of the Hemichordata. It is some years now since Bateson 



1 Fowler, G. H., "Morphology of Rhabdopleura Normani," Leuc- 

 kart's Fest., 1892. 





