DEVELOPMENT OF THE CEPHALOPODA. 41 
radiating granular fringes (fig. 2 A). They are often placed 
deeply in the yelk. 
These autoplasts are not such exceptional bodies to-day as 
they were three years ago when I first found them.! Gotte 
has found that the deep yelk of the hen’s egg continues to 
segment after the superficial cleavage products have been 
formed.' Balfour has found the yelk of the Shark’s egg full 
of bodies comparable to these autoplasts. I believe that the 
matter may be viewed thus :—a first segregation furnishes 
the patch of formative matter at one pole, which subsequently 
exhibits the phenomena of cleavage. Independently of and 
subsequently to this, segregation of formative matter goes on at 
numberless points of the egg’s surface or deeply. These 
latter segregations are the autoplasts. If it be asked “ whence 
comes the ‘formative matter’ and what is it?” the reply is, 
‘“‘from the original egg-cell and spermatic filaments, and it 
continually nourishes itself on the interfused particles of food- 
yelk resulting from the metamorphosed cells of the inner 
egg-capsule of the ovarian egg.” 
The first appearance of the Pen-sac in Loligo and Octopus. 
—In the October number of this Journal for 1874 I have 
given a diagrammatic figure of a section of part of an embryo 
of Loligo at a time when the rudiments of various organs— 
eyes, ears, mouth, foot, rectum—first appear. The Pen-sac 
is there shown to originate as a space enclosed by the 
upgrowth of a ring-like wall of the mantle, the margins of 
which close together by later growth. ‘This and earlier as 
well as later stages I have studied by means of sections of 
embryos hardened both in osmic and in picric acids, and sub- 
sequently mounted and now preserved in Canada balsam. I 
have also made sections of Octopus at corresponding periods, 
and I find that in this genus the fossa for the pen-sac is deve- 
loped, but its margins never close in. It is evanescent. The 
same is true of Argonauta. 
First appearance of the alimentary canal.—Passing over 
many matters of much interest which I have not space now 
to describe or illustrate, I shall here draw attention to the 
first appearance of the alimentary canal, and at the same 
time point to some facts bearing on the question of “ germ- 
layers” in the Cephalopoda. 
From the mouth a pharynx, with salivary glands as 
1 At one time I thought it possible that the autoplasts were vacuoles, or 
rather, drops of differentiated alouminous matter, izéo which the klastoplasts 
seut outgrowths or budded off celis. This view is taken by Oellacher with 
reference to certain vacuole-like bodies occupied by one or two cells in the 
egg of osseous fish. On testing this hypothesis I have rejected it, for there is 
no doubt that the autoplasts are dense, solid bodies like the nuclei of cleavage 
segments, and no such hypothesis accounts for the autoplasts of Octopus. 
