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MR. E. RAY LANKESTER ON THE 
No. IV. The growth of the Ovarian Egg of Loligo and Sepia. 
The following observations were made during the months of February, March, and 
April, at Naples, in 1872*. The eggs of Loligo were obtained in abundance from the 
fishermen, as the spring advanced becoming more common. ‘They were preserved in a 
basin into which a jet of sea-water was allowed to run continually; others were sunk 
in a basket in the fishermen’s harbour at Santa Lucia. I chose the eggs of Loligo 
rather than of Sepia for the purpose of commencing the study of the development of 
the Cephalopoda, because the egg-envelopes are colourless, and the egg itself sufficiently 
small to be transparent and easy to examine in the living state. The eggs of Sepia, on 
the other hand, require very careful treatment in order to remove the dark-coloured en- 
velopes, and are even then unwieldy objects for examination with high powers in the 
fresh state. The first part of the observations recorded below relate actually to the 
ovarian egg of Sepia, on which I found it more convenient (from the size of the eggs 
and from the fact that I possessed well-preserved ovaries of that genus) to carry out 
inquiries as to the mode of building-up of the egg previous to fertilization, and as to the 
significance of its basket-worked tunic. At the same time I have made many parallel 
observations on the ovarian eggs of Loligo itself; and I believe that it may be asserted 
with full confidence, that the ovarian egg of Loligo differs from that of Sepia only in 
the size to which it attains. 
In examining the progressive development of the deposited eggs of Loligo, I adopted 
the following method of manipulation. One of the finger-like colourless strings of the 
eggs being taken, I removed the outer coating of gelatinous matter, so as to expose the 
deeper gelatinous material which forms a separate capsule to each egg, the capsules 
being grouped longitudinally in four series around a central gelatinous string or axis; 
then with the scissors one, two, or three eggs were easily detached in their capsules and 
placed on the compressorium, which was allowed to press but very slightly on them. 
In this way (the ege being an elongated ovoid) a lateral view was of course always 
obtained. To obtain what I may call “a polar view” (that is, a view of the egg as 
seen from above when it is made to stand on end) is by no means so easy. I found the 
best way to be to cut a small diamond-shaped hole in a piece of cardboard, and, after 
having removed as much of the gelatinous investment of the egg-capsule as possible, by 
the aid of delicate forceps, to place the egg on end in the hole, with the pole to be 
observed uppermost. Then, keeping it well moistened with sea-water, the little piece 
of cardboard with the egg was placed in the compressorium, and the upper glass of that 
* Jan. 1875.—The portion of this memoir now published relates only to the ovarian ovum. It stands as 
it was read in March 1874. The rest of the memoir relating to Zoligo has been withdrawn for the purpose 
of incorporating new observations. An abstract of my observations (both those of 1872 and 1874) relating to 
the later development of Loligo, illustrated by two plates, is published in the Quart. Journ. Microsc. Science, 
Jan. 1875. In 1874, owing to the arrangements of Dr. Donrn’s zoological station, L was enabled to obtain 
abundant supplies of Zoligo embryos in all stages of development. 
