November 23, 191 1] 



NATURE 



109 



ater, which was perfectly clear, the light grey bottom 

 jwas still cracked and apparently unsoftened, and there was 

 Inot a trace of life of any kind. In the south canal the 

 Ibottom was generally dry, with, however, every here and 

 |there pools of water measuring about one metre across, and 

 tin these also there was no trace of life. I learned that 

 anglers never fish in these canals, because they know that 

 they will catch nothing. 

 In the afternoon I revisited the north canal, and instead 



f following the big pool westwards, which promised 



lOthing new, I turned to the right and followed it east- 

 wards towards the north-east corner. I had not gone very 

 "ar before I encountered a phenomenon of which I had 



Iready perceived the possibility, namely, a premature 

 esurrection resulting in widespread death. This part of 

 he canal was apparently dry, in the sense that the bottom 



as exposed to the air, but nevertheless moist enough to 

 le called wet. Owing, probably, to a slight general rise 

 f the ground-water of the neighbourhood, enough water 

 lad been able to filter through the mud of the bottom and 

 ;o rise to the surface and overflow, producing a very 

 ihallow pool (q), not more than 2 or 3 centimetres deep 

 »F more than a metre across. The wetting of the mud 

 >elow by this infiltration must have aroused the sleepers, 

 who then all started to rise at the same time. But when 

 hey released themselves from the mud there was not 

 inough water to fioat them all, and a formidable struggle 

 or existence was going on at the time of my visit, and the 

 [uantity of dead and dying fish lying all round the edges of 

 he pool furnished sufficient evidence of its fierceness. The 

 »oor fish would no doubt have willingly re-buried them- 

 elves and so saved their lives when they perceived their 

 nistake, but the stronger ones, which were in possession 

 >f the only part of the pool which could be called liquid, 

 :ept shouldering them outwards on to the mud, where they 

 lied in the air. When I left the struggle was still going 

 m, and it looked as if the level of the water was falling, 

 o that it is unlikely that many, if any, would be able to 

 etrieve their mistake by burying themselves again. As I 

 eft for England the next morning 1 was not able lo 

 ontinue my observations. 



Although the years vary much as regards humidity, and 

 n dry summers the supply of water in the ditch has often 

 alien to a pretty low ebb, I was informed that the last 

 ime that the ditch became quite dry was in the year 1814, 

 .Imost a hundred years ago ; therefore the experience of 

 he summer of 19 11 must have been a new one for all the 

 ■sh in the ditch, yet the general manoeuvre of protective 

 urial was carried out without a casualty. In order to 

 ccomplish this a fine instinct was necessary to perceive 

 he impending drying up of the canal, and then commence 

 he operation betimes so as to finish it before desiccation 

 fSiS complete. 



It must be remembered that the area of canal having 

 he muddy bottom, which alone is capable of receiving 

 hem, is very restricted ; and from the number of fish that 

 ame out of it in the short time that I was observing they 

 lust have been packed very closely, and in such an orderly 

 ^ay that, with the return of water in sufficient quantity, 

 tiey were able to take to it again apparently without 

 aving suffered at all. 



Although the instinct of the fish seems to have sufficed 

 3 make them foresee and provide for the dryness, it does 

 ot seem in all cases to have been sufficient to enable them 

 3 judge correctly the right moment for beginning their 

 Biease. 



Of the different species which inhabit the waters of the 

 itch, the carp and the tench have the habit of burying 

 jiemselves in the mud every winter; but the perch and 

 he pike have not this habit ; both can be caught at any 

 ime in winter, even under a covering of ice ; yet both the 

 >ke and the perch must have buried themselves with quite 

 s much skill as the carp or the tench. 



But in a climate like that of this part of France shallow 



ikes and ponds may suffer shortage of water by congela- 



on as well as by evaporation ; and the Prince informed 



|»e that he remembered one winter when in many places 



ne water of the ditch was frozen almost, if not quite, to 



ottom, and quantities of pike and perch were frozen 



he ice. This form of desiccation did not prompt them 



Iv refuge in the mud. 



NO. 2195, VOL. 88] 



It is evident that if the summer of 1911 had marked 

 the beginning of a secular period of dryness, such that the 

 canals were not again to be flooded, the fish which took 

 to the mud in that summer would be kept there. They 

 would die and decay in situ, and would be perfectly pre- 

 served in well-arranged though crowded masses. Eventu- 

 ally, if the change of climate was final, they would form 

 a rich and interesting bed of fossil fishes. But the interest 

 would depend not only on the abundance of fossils in the 

 muddy matrix of one part of the trough-like forma- 

 tion ; it would be intensified by their complete absence in 

 the hardened marly matrix of the other part. 



Before serious drying took place the ditch, or trough, 

 was covered by a continuous sheet of water in which the 

 fish and other creatures could circulate freely to all parts. 

 So soon, however, as actual desiccation appeared to be 

 imminent, the fish must have concentrated themselves in a 

 body over the districts of muddy bottom in which they 

 knew they could take refuge as a last resort. When 

 desiccation was complete every fish in the ditch, without a 

 single exception, had succeeded in burying itself in one or 

 other of these restricted areas of mud. Not one of them 

 appears to have made the mistake of seeking refuge in the 

 marly bottom. When completely dry the ditch, or trough, 

 consisted of two formations, the more e.xtensive consisting 

 of hard sandy marl and destitute of life, the less extensive 

 consisting of soft mud and teeming with aquatic life. 

 Further, the two formations are contiguous as well as 

 contemporaneous, and together they cover an area of not 

 more than eight hectares. 



As illustrating the geological significance of the facts 

 just recorded, the following passage may be quoted from 

 Sir Archibald Geikie's " Text-book of Geology " (1903). 

 p. 1003 : — 



" The water basins of the Old Red Sandstone might bf> 

 supposed to have been, on the whole, singularly devoid of 

 aquatic life, inasmuch as so large a proportion of the red 

 sandy and marly strata is unfossiliferous. In some of the 

 basins, where the sediment is not red and sandy, it is 

 evident that life was extremely abundant, as is shown, 

 for example, by the vast quantities of fossil fishes entombed 

 in the grey bituminous flagstones of Caithness and Orkney. 

 It may be observed that where grey shales occur inter- 

 calated among red sandstones and conglomerates they are 

 often full of plant remains, and may contain also ichthyo- 

 lites and other fossils which are usually absent from the 

 coarser red sediments. There would appear to have been 

 occasions of sudden and widespread destruction of fish life 

 in the waters of the Old Red Sandstone, for platforms 

 occur in which the remains are thickly crowded together, 

 yet so entire that they could not have been transported 

 from a distance, and must have been covered over with 

 silt before they had time to decay and undergo much 

 separation of their plates." 



The last sentence of this passage seems to describe the 

 actual condition of the muddy bed of the moat round the 

 Park of Marchais as it would appear to a geologist^ after 

 the necessary interval of time had elapsed which is re- 

 quired to separate the date of the death of the crowd of 

 fishes which voluntarily entombed itself in the mud before 

 desiccation was complete, and the date at which ^ the 

 stratum of mud and remains so produced would be entitled 

 to rank as a geological formation. I do not know if 

 there are any adequate data for arriving at a trustworthy 

 estimation of the probable length of this interval. It is 

 quite distinct from what is understood as the age of the 

 geological formation. 



The barren districts of sandy and marly matter at the 

 bottom of the ditch would, after the lapse of the same, or 

 perhaps a shorter, interval furnish perfectly unfossiliferous 

 strata, which would suggest to the geologist of later date 

 that the water basin in which it had been laid down had 

 been singularly devoid of aquatic life. Yet, in a sense, it 

 would not be inaccurate to say that the water basin in 

 which the muddy strata holding the crowded fish remaiirs 

 had been " laid down " teemed with life, and that thf- 

 barren strata had, in the same sense, been " laid down " 

 in water devoid of aquatic life, although the two bodins 

 of water formed one continuous sheet of very restricted 

 dimensions. It would seem, therefore, that a material 

 barrier is not necessary to separate even a SDialJ body of 



