162 DONALD WALTON DAVIS 
INTRODUCTION 
This paper deals with the processes of fission and regeneration 
and their variations in the sea-anemone Sagartia luciae Verrill, 
together with the relations of these processes to the distinguish- 
able morphological types and to the life history of the species. 
Many descriptions of isolated instances of multiplication by 
asexual methods in Actinians have been published. Among 
these are somewhat detailed accounts of the external aspects of 
the process of fission. The present paper stresses the internal 
phases of this process, to which little attention has heretofore 
been paid. A few studies have been made of the regenerative 
processes following the separation, but no connected account of 
the external and internal features of division and regeneration in 
a single species has hitherto appeared. Moreover, in species of 
Aiptasia, where our information is most nearly complete, the 
processes are markedly different from those in S. luciae. 
Variations in the details of form of Actinians have long been 
the subject of passing comment or of more or less serious study. 
That these variations, more specifically variations in the num- 
ber of siphonoglyphs, are related to processes of reproduction 
was first suggested for Metridium dianthus by Parker ('97) and 
has been demonstrated in that species by Hahn ('05). A 
similar suggestion as to S. luciae was made by Davenport ('03). 
This suggestion has been confirmed in the observations here 
reported. Owing to the presence in S. luciae of external mark- 
ings which are not found in other anemones and which give 
evidence of fundamental internal structures, it has been possi- 
ble to determine the relation of the processes of asexual repro- 
duction to these internal structures. The significance of studies 
of the asexual processes of S. luciae is increased by failure to 
obtain thus far any stage in its ontogenetic development. 
For various reasons, more complete knowledge of the life 
history of this species is desirable. Its appearance at New 
Haven about 1892 has been reported by Verrill ('98); its rapid 
increase and gradual dispersal have been described by Verrill 
and by Parker ('02) . It is now the most abundant sea-anemone 
