STUDIUS IN SPICULE FORMATION. 283 
Studies in Spicule Formation. 
II—Spicule Formation in Alcyonium digitatum; with 
Remarks on the Histology. 
By 
W. Woodland, 
University College, London, 
With Plates 16 and 17. 
HISTORICAL. 
Consiperinc how common a form on both English and 
Continental coasts is the massive colony of Alcyonium 
digitatum, it is the more surprising that the very conspicuous 
and characteristic skeleton appertaining to this species has 
not been more fully investigated from its developmental 
aspect than it hitherto has. Figures, verbal descriptions, 
and nomenclatures of the various forms of the adult 
Alcyonarian spicule are plentiful enough, but, so far as I 
have been able to ascertain, the manner of development of 
this skeletal element has, up to the present, never been com- 
pletely worked out." 
A. von Kolliker (1), who was one of the first to study 
Alcyonarian spicules, supplied in his ‘Icones histologice’ 
(published in 1864) a full description and classification of 
1 The limited scope of the present paper—relating to the spicules of 
Aleyonium digitatum only—is solely due to the fact that I have as yet 
been unable to visit the Naples Biological Station in order to obtain and 
properly preserve specimens of other genera and species of Alcyonaria. 1 
hope, however, at some future date to fully investigate spicule-formation in 
Alcyonaria generally when the opportunity for obtaining the material offers 
itself, 
