The Ernhryology of Patella. 
3 
The spawning season of Haliotis and Fissurelia had passed; 
I determined to try artifical impregnation on Patella and was 
delighted to obtain a large number of fecundated eggs at the 
first attempt. It was not until the first of Nov. that the ova 
were sufficiently matured to allow its successful performance. 
The spawning season continued from that time until the middle 
of January. So far as I know this is the first instance of arti¬ 
ficial fecundation*) having been successfully tried upon any of 
the Gasteropods and it was considered of sufficient importance 
to publish a notice of the same in the „Zoologischer Anzeiger“, 
VIII. Jahrg. April 27 eb ’ p. 236. 
Unfortunately I was seklom able to keep the larvae alive longer 
than ten or twelve days, at the end of which time all the thou- 
sands that at first were apparently healthy became so abnormal 
and dwarfed that it was impossible to use them for study. Only 
once did I succed in obtaining a few embryos with a normally 
developed nautiloid shell. PI. V, Fig. 66. Others which had been 
kept twice as long, or fourteen days, developed no shell at all alt* 
hough the conditions were apparently the same in both cases. 
Various unsuccessful attempts were made to obtain larvae 
by fishing from the surface. 
The mature ova of Patella when taken from the ovary are 
of a bluishgreen color and measure 0,12 mm. in diameter. They are 
protected by a very thick transparent chorion whose outer surface 
is covered with a number of shallow indentations between which 
is a much greater number of very small dots, which when highly 
magnified are also seen to be indentations, but smaller and more 
thickly distributed than the former. The bottom of each of these 
small pits is continuous with a fine line or canal (?) extending 
radially from the outer to the inner surface of the chorion. In 
profile the outer surface has the appearance represented in PI. I, 
0 I believe the ova of Haliotis and Fissurella could also be artificially, 
fecundated, as the same conditions prevail in them as in Patella, but the season 
had passed before it occurred to me to try it. It was not until after my experi- 
ments upon Patella were completed that I learned indirectly through v. Ihering’s 
paper of W. H. Dall’s observations on the „Extrusion of the Sexual Products of 
Patella“ by means of a fusion and subsequent rupture of the walls of the right 
organ of Bojanus and that of the ovary or testis, during the spawning season, 
thus affording free communication between the ovary or testis and the outer world. 
11 * (151) 
