ON AUTO-PARTHENOGENESIS IN ARBACIA AND 



ASTERIAS. 



OTTO GLASER. 



(Front the Marine Biological Laboratory at Woods Hole and the Zoological 

 Laboratory of the University of Michigan.) 



The unfertilized ova of Arbacia eliminate substances which 

 discolor the sea-water, but when the same eggs are undergoing 

 impregnation, the discoloration of an equal amount of sea-water 

 in unit time, is roughly half again as much ('i4 2 ). Hand in 

 hand with this fact goes the discovery that both Arbacia (punc- 

 tulata) and Asterias (forbesii) ova, are measurably smaller in 

 volume after fertilization than before ('I3 1 , 'I4 1 )- These ob- 

 servations led me to begin an investigation which might throw 

 some light, not only on the nature of the substances lost, but on 

 the further question whether their elimination is significantly 

 associated with the initiation of development. Not more than 

 a beginning has been made, but some of the preliminary, chiefly 

 qualitative, results are sufficiently interesting to be reported at 

 the present time. 



My earliest experiments consisted in a series of attempts to 

 find what sort of substances could be gotten out of the eggs. I 

 therefore prepared solutions in sea-water from ground, laked, or 

 extracted ova. These preparations when tested with sperm 

 exhibited the properties which had been described by F. R. Lillie 

 for egg-secretion ('12, 'i3 2>3 ). Emphasis must be laid on the 

 power of these extracts to activate the sperm ; on their chemotactic 

 effect; and on their sperm-agglutinating as well as sperm-paralyz- 

 ing capacities. Addition of the extracts in certain concentrations 

 to normally fertilized eggs, resulted in a retardation of develop- 

 ment; normal blastulse instantly slowed their movements, and 

 underwent a noticeable increase in volume when subjected to 

 the extracts. Similar observations were made on the larvae of 

 Arenicola whose rate of movement was also slowed down, to be 

 followed instantly by an outflow of their yellow pigment and a 

 slight and reversible agglutination. 



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