A name known all remain always attached that Jacques Loeb, who recently re admirable summary of the countless work he has devoted to its study.
This article is not a historical criticism, but only exposed the current state issue, we will take care of Loeb presqu'exclus ement works, reserving call, need arises, to other authors who have online proofreading course studied parthenogenesis artificial Giard, Delage, Morgan, Wilson, Lillie, etc.
We will analyze specially Finally, the current results parthenogenesis new method called traumatic, due to Battalion.
Once Loeb showed that it was sufficient to deal with mature sea urchin eggs, freshly laid virgins for some time one hour, for example, sea water concentration higher than normal, to get at the beginning of parthenogenesis when then delivers the water normal i need help writing my thesis sea.
Loeb insisted same time that this purely osmotic method was not an exact imitation fertilization by sperm yolk sac, constant characteristic latter, not formed by the action of hypertonic solutions the results are completely irregular, sometimes zero, sometimes satisfactory development is very term paper writer slow, the clearly pathological larvae mortality is thus less, when eggs are fertilized just after essay writing service usa spawning. After thirty-six within forty-eight hours more membrane shape, although still fertilize eggs leave but that is abnormal, certainly exceptional in kind.
STUDY OF FERTILIZATION Loeuf Especially the absence yolk sac that struck Loeb considered, because it as visible manifestation profound changes in chemistry fertilized egg it is this membrane that he sought above all to reproduce artificially managed treating sea urchin eggs by the first ethyl acetate and then, gradually as his research by a range of other body all fatty acids, benzene, toluol, amylene most hydrocarbons, soaps, bile salts, saponin, alkalis, etc. All these bodies, very difiereuts each other, have common action whether to act for a few minutes on egg, then that puts celurci normal sea water, yolk sac is formed without fail, one way absolutely constant, except in the case, of course, of eggs for too long. The membrane once formed, sees the egg to prepare first of fusion generally, it is abnormal even completely abort an egg, before it can produce, seems deeply affected undergoes real liquétaction, particular disintegration bringing general name cytohjse by the action of these different substances, Loei so well reproduced yolk sac development even put on but caused a deadly cytolj'se same time. ' â ongea fortunately also experience their effects on eggs previously treated with sea water liyp M tonic they too formed a membrane unlike we dissertation writing consultant have seen, most suffered no subsequent cytolysis could develop even gave larvae free-swimming, which this time were vigorous good health.
From this moment, Loeb had the brilliant intuition of a kind of antagonism between the agents causing cytolysis, firstly, hypertonic solutions, second glimpsed the same time possibility of a method perfectioïwcc artificial parthenogenesis, and results were atist'aisants he found no way brought progress, too, to see in normal fertilization process comparable this overlay two antagonistic actions. Ia nnHhode advanced artificial parthenogenesis, Decou STUDY OF FERTILIZATION green LŒUE by Loeb is now emploj ed in most laboratories principle here, the less respect the sea urchin Strongylocentrotus purpuratus minutes to stay in mixture consisting of butyric acid in proportion. decinormal a solution for seawater G. passage during normal processing in minutes in sea water for a minute with a hypertonic solution, obtained adding to sea water, normal sodium chloride solution back final in ordinary water sea. We do not insist on accessories precautions, intended to put the eggs in optimal ventilation conditions, temperature, etc.
By process, Loeb gets up very successful.
In addition, developing these parthenogenetic larvae hardly differs from that of control larvae is somewhat slower. The larvae are smaller, but for reasons of foreign morphological at issue before us. It remains to consider two very important detail what problems the combined action mechanism fatty acid, for example, sea water hypertonic? How can it compare to normal fertilization? The first solution is still research thesis incomplete has yet many assumptions but they are ingenious, clearly show depth the originality of designs Loeb, we can resist the pay to do my paper urge to briefly outline we will also theory scope that it greatly exceeds the limits fertilization physiology. Let's start with the good set discussion databases only hypertonic solutions, fatty acids alone like bodies are powerless to ensure parthéno II development so that details vary by species method same race to which a case. We know that Del age obtained by different process, ideal result of a development parthéiiogénétique poursu until i vetat adult. The limits this article permit us to analyze detailed principle method. We refer readers original work. STUDY OF FERTILIZATION LŒUî complete genetic To the sea urchin egg celurci is obtained regularly, essay online help otherwise, by a combined action of these two factors. What is, first, the action of hypertonic solutions on unfertilized eggs of the sea urchin? This action is far from always the same, which is compared with that we have higher earnings volatility purely osmotic hypertonic solution dissolution method contains a sufficient amount of oxygen, the treated eggs disintegrate when it puts the normal sea water but not the disintegration product removes oxygen by passing a stream of hydrogen in hypertonic solution prevents oxygen to act on the eggs, adding thereto a trace cyanide potassium chloral hydrate.