ON THE EFFECT OF VARIATIONS IN THE TEM 

 PERATURE UPON THE PROCESS OF 

 ARTIFICIAL PARTHENOGENESIS. 



ARTHUR W. GREELEY. 



In a previous paper ' it has been shown that the unfertilized 

 eggs of Astenas may be made to develop parthenogenetically by 

 exposing them for a definite length of time to a temperature of 

 i C. to 7C. These experiments were the outcome of others 2 

 in which it had been demonstrated that the cells of Spirogyra and 

 some Protozoa may be made to lose water by lowering the tem- 

 perature. From these observations on the effect of low tempera- 

 ture on simple animal and plant cells, it is made probable that 

 the artificial development of the Asterias egg by means of a low- 

 ering of the temperature is brought about by an extraction of 

 water from the protoplasm, just as if the eggs had been placed 

 in a solution of a higher osmotic pressure than that of the sea- 

 water. This latter method has been found to be successful for 

 the Astenas as well as the Arbacia egg by Dr. C. H. Neilson. 

 Beyond the fact that a low temperature brings about certain 

 changes in the physical condition of the protoplasm that result 

 in a loss of water, nothing is known concerning the action of low 

 temperatures upon the egg. 



In the course of experiments on artificial parthenogenesis it 

 has been noted by several observers that the experiment must 

 be performed within certain very narrow limits of temperature. 

 Above or below these limits of temperature, of which 20 C. 

 may be taken as the mean, the experiments have failed with any 

 of the methods heretofore used to obtain artificial parthenogen- 

 esis. In order to determine, if possible, the role which tempera- 

 ture plays in this process, Dr. Loeb suggested that I repeat some 

 of the well-known experiments in artificial parthenogenesis, test- 



1 Greeley, American Journal of Physiology, VI., 1902, p. 296. 

 2 Greeley, ibid., VI., 1901, p. 122. 



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