XXXII 
EXPERIMENTS ON ARTIFICIAL PARTHENOGENESIS IN 
ANNELIDS (CHATOPTERUS) AND THE NATURE OF 
THE PROCESS OF FERTILIZATION’ 
I. INTRODUCTION AND METHODS 
My preceding papers on artificial parthenogenesis’ had 
proved that by an increase in the osmotic pressure of the 
sea-water the eggs of many, if not all, Echinoderms can be 
caused to develop parthenogenetically. Two new problems 
presented themselves for immediate consideration. The one 
was to raise the parthenogenetic larvee until they were sex- 
ually differentiated, in order to decide whether or not they 
are of uniform sex. The second problem was to try whether 
artificial parthenogenesis is confined to the group of Echino- 
derms or whether it is a more general phenomenon. As the 
means for the raising of sea-urchins were not available at 
Woods Hole this year, the former problem had to be post- 
poned. The solution of the second problem, however, was 
possible, and yielded the result that the unfertilized eggs of 
Cheetopterus, a marine Annelid, can be caused to develop into 
swimming ciliated larve (trochophores). A short preliminary 
report of this result has been published in Science.’ 
In experiments on parthenogenesis the greatest precau- 
tions are necessary to exclude the possibility of a contamina- 
tion of the eggs by spermatozoa. I purposely selected 
Cheetopterus for my further experiments on account of the 
possibility of discriminating between and separating the 
females and males. If the experimenter handles females 
and males in the same experiment or with the same instru- 
1 American Journal of Physiology, Vol. IV (1901), p. 423, 
2 Part II, pp. 539, 576, 624, and 638. 3 Science, Vol. XII (1900), p. 170. 
646 
Digitized by Microsoft® 
