EXPERIMENTS WITH THE Eccs or MOoLuuscs 269 
without segmentation. Kostanecki! found this in his experi- 
ments with Mactra and the writer confirmed this for Lottza. 
It must be remembered, however, that these are only short- 
comings of the method, and it was therefore to be expected that 
different methods would give different results. 
The writer did not succeed in causing artificial partheno- 
genesis in the eggs of Cwmingia, a mollusc at Woods Hole, by 
any of the older methods, but Wasteneys and he succeeded in 
not only causing these eggs to develop, but also to develop with 
normal segmentation by treating them with ox blood. The 
method used was as follows. The eggs were sensitized to the 
effects of serum by placing them for from two to four minutes 
into a 3/8 m solution of strontium chloride. They were then 
placed for five minutes in ox serum rendered isotonic with sea- 
water and diluted with an equal part of a m/2 solution of 
NaCl+CaCl,+ KCl. After having been freed from all traces 
of serum by repeated washing in a Ringer solution, they are 
transferred for sixty minutes into hypertonic sea-water (50 c.c. 
sea-water+8 c.c. 24 m NaCl). Control experiments showed 
that the treatment with serum is an essential factor in this 
process.” 
This latter experiment shows the close similarity of the 
methods of artificial parthenogenesis in various groups of 
animals. 
1 Kostanecki, ‘‘Zur Morphologie der kiinstlich parthenogenetischen Ent- 
wicklung bei Mactra,’’ Arch. f. mikroskop. Anat. u. Entwicklungsgesch., LX XII, 
327, 1908. 
2 Loeb and Wasteneys, ‘‘ Fertilization of the Eggs of Various Invertebrates by 
Ox Serum,’’ Science, XXXVI, 255, 1912. 
