[3] CAUSE OF THE GREENING OF OYSTERS. 795 



is mingled with that of the sea, and which is poured into our reservoirs 

 during the spring-tides, to again be mixed with the waters of the river; 

 in the second place, the action of a moderate temperature ; then the sun 

 and the northeast wind which brings about the above-mentioned thermal 

 conditions ; in fine, to the mode in which the parks are managed, accord- 

 ing to methods which have been adopted after prolonged experience." 



In the Medecin Malgre lui, when Sganarelle explains to Geronte why 

 his daughter is mute, the reasons which he gave are, to say the least, 

 quite as plausible as the causes invoked by M. Goubeau de la Billenerie 

 to account for the r/reewiw</ of oysters. He invokes all the elements; 

 the sun, the northeast wind, and then the moderate temperature along 

 the banks of the Seudre, from September to April, that is to say, that 

 prevailing during the coldest part of the year. This is taking into ac- 

 count a great many causes in order to produce such a simple effect, and 

 reason is confounded when it is inquired what share each of these many 

 causes has had in producing the observed phenomena. The criticism 

 of M. Goubeau do la Billenerie is far from as valuable as the incomplete 

 investigation by Gaillon. 



In his Voyage cCexploration sur le littoral de la France et de VltaUe, M. 

 Coste does not himself directly enter upon the consideration of the 

 question which now occupies our attention, lie contents himself with 

 reporting the various opinions which others have expressed, and merely 



enunciates the following conclusion, p. 118 : 



******* 



'' Of these three opinions, that which attributes to the nature of the 

 soil the power of greening [oysters] appears to be the most in accord 

 with the actual facts of the case." 



We shall see in the sequel that the nature of the soil is not in any 

 sense the immediate cause of the viridity of these mollusks. This opin- 

 ion, like the others, was not expressed by M. Coste as his own, but 

 only as the most plausible amongst those which he had enumerated. 

 A man of the character of the learned professor of the College of France 

 would not be content to discuss this subject with the intention of merely 

 playing upon words. 



In this case, as in many others where vital processes come into play, 

 the science of chemistry has been fruitless in the investigation of the 

 cause of the viridity of oysters. M. Berthelot, at the request of M. Coste, 

 sought to discover what was the true nature of the matter to which the 

 coloration of the branchiai of the oysters of Marennes was due, and the 

 only results which he obtained from analyses were of an absolutely neg- 

 ative character. 



" Summarizing our results," says the celebrated chemist, "the coloring 

 matter found in the oysters of Marennes does not resemble that of blood, 

 that of the bile, nor vegetable or animal coloring matters generally. 

 The coloring matter of the blood contains, it is true, some iron, but the 



