TRANSACTIONS OF WAGNER 
ON THE LIFE HISTORY OF AN ECONOMIC CUTTLEFISH OF JAPAN 
in the present species causes, therefore, the occurrence of the seminal recepta- 
cles on the buccal membrane which indicates the habit of depositing demarsal 
eggs. As Iam convinced from these anatomical data, the present species can 
with reasonable certainty be said to discharge eggs which have not yet been 
observed, but will be detected in future imbedded in masses of a Jjelly-like sub- 
stance deposited on the sea bottom or fixed to something on or near the bottom, 
at a depth accessible only by means of a proper dredging implement. On the 
other hand it has been made out by my experiments that the artificially fer- 
tilized eggs which have been reared so far as to be divided into segments, are 
denser than sea water. They must, therefore, be demarsal eggs, affording a 
strong positive evidence for my assumption just given. 
ARTIFICIAL FERTILIZATION 
In Oegopsid Cephalopods, as far as I have been able to ascertain, the re- 
sults of artificial fertilization have not as yet been fully described on any species. 
In 1912 I attempted it with Watasenia scintillans, but was obliged to break off 
the experiment before it succeeded. Last summer I was so fortunate as to 
have a good opportunity of undertaking the experiment on Ommastirephes 
sloani pacificus, which was done twice. On the first occasion, on August 27, 
1919, the material employed for the purpose consisted of one male and one 
female which were caught two miles off Saigo, Oki Islands. They were 
brought to me at 11 o’clock p. m., when they were still active. I took eggs out 
of the oviducts, and the spermatozoa from the spermatophores contained in 
Needham’s sac of the male. The sexual elements were mixed together by the 
dry method and put into a basin containing sea water brought in from the 
offing. The eggs thus treated all sank to the bottom of the basin and did not 
float as in the case of Watasenia above referred to. They developed fairly 
rapidly, attaining the blastula stage by the next morning. The segmentation 
was partial and the cleavages extended on the yolk sphere nearly as far as in 
the case of Loligo. Towards noon the eggs began to die and by 3 o’clock p. m. 
all were dead and had become opaque. 
In this experiment the eggs which developed were about 20% of the 
whole eggs treated, another 20% were dead shortly after the fertilization, and 
the remainder at last showed no sign of fertilization, although they remained 
as if living for some time. ; 
