ARTIFICIAL PARTHENOGENESIS IN ANNELIDS 265 
Lefevre has made a very interesting observation on the 
behavior of the polar bodies. As a rule, the first polar body 
given off from the egg when it is fertilized with sperm divides 
only once, and the second polar body does not divide. Lefevre 
observed, however, that both polar bodies of the eggs treated 
with acid pass through a series of mitotic divisions and give 
rise to miniature embryos of sixteen cells. He compares these 
facts with Francotte’s observation that in Prostheceracus, a 
turbellarian, the first polar body is relatively large and can be 
fertilized by a spermatozoon and even develop into a gastrula. 
As a rule the cleavage was normal and so were the larvae; 
but they did not rise to the surface of the water like those 
derived from fertilized eggs. Hence they easily fall victims to 
bacteria. 
6. For the sake of completeness, some of the older experi- 
ments on artificial parthenogenesis in annelids may be briefly 
mentioned, although the methods used are not very satisfactory. 
In Amphitrite eggs could be caused to develop by treating them 
with sea-water whose calcium content was raised.’ 
Fischer produced artificial parthenogenesis in the eggs of 
Nereis by treating them with a hypertonic solution.? Bullot 
succeeded by the same method, in the eggs of Ophelia.* 
Again we may state that the methods of artificial partheno- 
genesis for annelids are essentially identical with those used for 
the eggs of the sea-urchins, except that the second factor is 
not quite so important. 
1 Loeb, Fischer, and Neilson, Pfliiger’s Archiv, LXXXVII, 1, 1901; Scott, 
Jour. Exper. Zool., III, 49, 1906. 
2 Fischer, Am. Jour. Physiol., 1X, 100, 1903. 
3 Bullot, Archiv f. Entwicklungsmechanik, XVIII, 161, 1904. 
