472 MAX MORSE 



2. When reagents are at all effective, they produce polar body 

 formation^ and early morulas, but none were found to cause 

 farther development. 



3. Such reagents as are effectual in causing even this develop- 

 ment in the unfertilized egg aid artificial hybridization with for- 

 eign spermatozoa, as far as could be determined, in no manner. 



4. Artificial hybridization was found to be possible in but one 

 instance, namely, the spermatozoa of the mollusk, Ilyanassa 

 obsoleta. 



5. Extract of sperm, made by killing the spermatozoa at 40°C., 

 did not induce egg development in Cerebratulus, nor in Arbacia. 



6. Lecithin from the hen's egg and from eggs and spermatozoa 

 of Arbacia produced no effect upon the eggs of Arbacia. 



7. The conclusions of Jacques Loeb concerning the role of H 

 and OH ions in artificial parthenogenesis are favored by these 

 experiments. 



MATERIAL AND METHODS 



The work was primarily planned to cover section 2 of the above 

 sets of experiments, using the clam worm found so readily in full 

 breeding season at the Harpswell Laboratory, South Harpswell, 

 Maine, during the summer months, from June until September, 

 but as explained above, it was necessary first of all to study in 

 detail the various reagents which have been used effectually in 

 other instances, but not at all, as far as I know, upon any nemer- 

 tean. In order to corroborate the work upon material from an 

 entirely different locality and under entirely different circum- 

 stances as to environment, etc., a study was made of the clam- 

 worm found at New Haven, Connecticut, which is sexually mature 

 during the months of March or April, according to the season. 

 Finally, the work upon Arbacia and some other forms was carried 

 on at the Marine Biological Laboratory, Woods Hole, Massachu- 

 setts. 



I am greatly indebted to the officers directing the three labor- 

 atories at which I worked, namely, the Harpswell Laboratory, 



1 The nucleus of the egg prior to fertilization rests in the metaphase of the first 

 polar body formation until the spermatozoon enters, when the mitosis proceeds 

 through anaphase and telophase. 



