Mabch 25, 1910] 



SCONCE 



467 



not showed: (o) Those that had conjugated 

 divided less rapidly for about a month, when the 

 difference became equalized. In no case did those 

 that had conjugated show a more rapid rate of 

 fission, even after more than a month. (6) Many 

 of those that had conjugated did not divide at all, 

 or divided but once or twice in an abnormal way, 

 then died. All those that had not been permitted 

 to conjugate lived and divided normally. (c) 

 Among those that had conjugated many abnor- 

 malities and monstrosities occurred, while none 

 occurred among those not permitted to conjugate. 

 Thus the experiments gave no indication of a 

 rejuvenating effect of conjugation. It was sug- 

 gested that conjugation might be preliminary to a 

 resting condition, in which unfavorable environ- 

 mental conditions are tided over. 

 Effect of External Agents upon Growth in Para- 

 mecium: A. H. EsTABEOOK, Johns Hopkins Uni- 

 versity. (Introduced by H. S. Jennings.) 

 Examination was made of the growth of Para- 

 mecium in pure distilled water, and in solutions 

 of sodium chloride, nicotine, strychnine nitrate 

 and alcohol, the results being compared with the 

 growth in hay infusion. 



It was found that the Cell after fission has a 

 strong tendency to grow in a perfectly definite 

 way, at a definite rate, the growth giving a defi- 

 nite curve. It thus grows in spite of the absence 

 of any food materials; in spite of the almost 

 complete absence of the usual salts in the water, 

 and in spite of the presence of actively injurious 

 chemicals that later kill the organism. Evidently 

 inner conditions give the animal a potential of 

 growth which it is difiicult to overcome. 



No evidence was found that by subjection to 

 chemicals a race of a given type can be trans- 

 formed into a larger or smaller race. 

 Does Lecithin Influence Orowth? A. J. Goldfabb. 

 (Introduced by T. H. Morgan, Columbia Uni- 

 versity. ) 



After referring to the chemical nature of leci- 

 thin, the speaker pointed out the role of lecithin 

 in the living cell. The evidence was then reviewed 

 upon which the generally accepted view is based 

 that lecithin exerts a marked acceleration upon 

 the growth of an animal. 



The speaker then described his own experiments 

 upon the same kind of animals as those used by 

 previous investigators. Emphasis was laid upon 

 the following: (1) the greatest pains had been 

 taken to free the lecithin from impurities; (2) 

 variations due to environmental factors were re- 



duced to a minimum; (3) the large number of 

 animals used rendered it practically certain that 

 the resulting data did not represent individual 

 variations; (4) the degree of variation for each 

 kind of animal was ascertained by comparing the 

 controls for each series and litter; (5) animals 

 given lecithin in doses ranging from subminimal 

 . to injurious showed no definite corresponding 

 increased growth. The utmost irregularity pre- 

 vailed. Approximately one half the animals grew 

 faster, one half slower than the respective con- 

 trols. The gain was well within the normal 

 variation. 



Regardless of the kind or dose of lecithin used, 

 or the manner of administering it, lecithin did 

 not accelerate the growth of animals. 

 Is the Stimulation toward Artificial Partheno- 

 genesis a Physical or a Chemical Process? J. F. 

 McClendon, Cornell Medical School. 

 I caused artificial parthenogenesis in the eggs 

 of Arabacia punctulata by the following agents 

 which stimulate muscle and produce haemolysis: 

 isotonic NaCl, and the following chemicals and 

 conditions in sea water: acids, alkalis, hyper- 

 tonicity, hypotonieity, ether, diminished oxygen, 

 KCN, heat, cold, induction shocks and mechanical 

 agitation; All of these methods probably in- 

 creased the permeability of the eggs, causing a 

 disappearance of the positive charge on the sur- 

 face and thus increasing the surface tension. A 

 band of greatest surface tension around the egg 

 would cause cleavage, contrary to Robertson, 

 whose experiment was vitiated by the fact that 

 the oil drop used as a model was fioating on 

 water. I found that just before cleavage the 

 pigment plastids migrated to the egg surface, 

 which, if they were charged negatively, would 

 result from the potential gradient produced at 

 the moment the egg surface became more per- 

 meable. The fact that CO, ajid catalase come out 

 of the egg and oxygen enters the egg, in increased 

 amount about the time of cleavage, indicates in- 

 creased permeability. The substances increasing, 

 the permeability may enter the egg later, although 

 their specific action was on the surface. The fact 

 that rise in temperature causes parthenogenesis 

 invalidates Loeb's deductions from the tempera- 

 ture coefiicient, and the factor common to fertili- 

 zation and artificial parthenogenesis is probably 

 physical, i. e., increased permeability. 



The Biological Cycle of the Hay Infusion: 

 LoBANDE Loss WooDBUTF and MoEEis S. Fine, 

 Yale University. 



