History oF ARTIFICIAL PARTHENOGENESIS 53 
a small amount ({ to 3 of 1 per cent) of KCl is added to the 
sea-water, the amphiaster of the first oocyte stage at once 
resumes its activity. “The maturation processes, including 
the extrusion of the first and second polar bodies and the 
concomitant changes in the form of the egg, succeed one another 
with the same regularity that obtains when the egg is fertilized.” 
Mead, however, observed no further development in these 
eggs. From these experiments he concludes that, in the normal 
fertilization of Chaetopterus, “the entering sperm stimulates 
these mitotic activities in a similar manner, i.e., by exerting 
a chemical influence on the egg and not by furnishing the egg 
with the organs of division.””’ This work of Mead’s which, in 
my opinion, occupies a distinguished position among cytological 
treatises, has been but little noticed in the literature of the 
subject. 
In 1899 Morgan! published some new and important obser- 
vations on the effect of hypertonic solutions upon the unferti- 
lized egg. He had discovered that if unfertilized eggs were 
treated with hypertonic sea-water, they began to divide without, 
however, developing into larvae. Morgan considered this 
cleavage an abnormal phenomenon, which was in no way com- 
parable to normal segmentation. “‘The form of the cleavage 
is totally different from that of the normal cleavage.’ Accord- 
ing to Morgan’s illustrations, the eggs appear to have developed 
to about the sixteen-cell stage, but not farther. ‘‘The time 
that it takes for a cleavage plane to pass through the egg is 
often very long in comparison to the time of normal division. 
The result is a mass of extremely minute granules or pieces. 
These pieces never acquire cilia and do not produce any form 
that resembles any stage of the normal embryo. Later the 
masses disintegrate” (pp. 454 and 455). Morgan’s aim was not 
to obtain artificial parthenogenesis, but to corroborate his former 
1 Morgan, ‘‘The Action of Salt Solutions on the Unfertilized and Fertilized 
Eggs of Arbacia and of Other Animals,”’ Archiv f. Entwicklungsmechanik, VIII, 448 
18939. 
