198 



NATURE 



{June 28, 1888 



of these, homologous with the nephridia of other worms, such as 

 Lumbricus, to which they are at all events suspiciously similar in 

 arrangement and structure? 



(3) What is the relationship of the large to the smaller 

 nephridia? Are they modifications of the latter, or independent 

 later developments ? 



(4) In either case the Platyhelminth system must be more 

 closely represented by the small nephridial bodies devoid of 

 internal openings and provided with a network of ducts such as 

 is found in Perichceta, Acanlhodrihts, and Megascolides, than 

 by the more specialized paired nephridia of such a form as 

 Lumbricus, 



Possibly the course of development as represented in living 

 forms may be somewhat as follows : — 



(1) A series of numerous nephridia present in each segment 

 devoid of internal openings, and connected by a continuous 

 network of ducts, as in Perichceta. 



(2) The aggregation of these smaller nephridia into tufts in 

 various parts, as in the posterior region of Acanthodrilus ; the 

 subsequent enlargement of certain of these nephridia and the 

 acquirement by them of secondary internal openings. It 

 is interesting to note in Megascolides that in the anterior 

 part of the body, where the small nephridia are scattered 

 over the whole body- wall of the segment, large nephridia 

 are absent, whilst they are present in the posterior region, 

 where the small nephridia are confined to a ring in the 

 posterior part of the segment. In this case, as the nephridia 

 become aggregated into tufts in the anterior part, the ducts 

 connecting them with those in the posterior region of the seg- 

 ment next in front will become fewer, until when, as in Megasco- 

 lides, only a single, modified, large nephridium remains on 

 either side anteriorly, there will be simply one duct from seg- 

 ment to segment uniting with a network of ducts in the region 

 where the small nephridia still persist. 



■ It is interesting to note that the aggregation of the smaller 

 nephridia, and on this supposition the modification of certain of 

 them to form the larger ones, commences in the posterior region 

 of the body. 



In certain worms, such as Acanthodrilus, the connection of 

 the network of ducts from segment to segment seems to have 

 b';en lost, at any rate in the adult : aggregation of these in the 

 neighbourhood of the setae, and subsequent modification, would 

 give rise to a certain number of nephridia in each segment 

 without any longitudinal duct. 



(3) The next stage is reached in such a form as Lattice, where 

 the longitudinal duct persists, but all trace of the smaller 

 nephridia is lost. 



(4) The final stage is present in most earthworms where, in 

 the adult, all traces of both small nephridia and longitudinal 

 duct are lost, though the latter is present, as in Lumbricus, during 

 development. 



These lead to three conclusions, two of which are practically 

 identical with those of Mr. Beddard : — 



(1) That the smaller nephridia without internal openings, 

 irregularly scattered, and with a network of ducts such as 

 are seen in Acanthodrilus, Perichceta, and Megascolides, are 

 homologous with the nephridial system of Platyhelminths. 



■ (2) That the larger nephridia typical of most earthworms are 

 secondary modifications of certain of the smaller ones subsequent 

 to their aggregation into groups ; the modified ones acquiring 

 each an internal opening. 



(3) That there is no homology between the longitudinal duct 

 of lumbricus, Lattice, Megascolides, &c, with that of the Platy- 

 helminths, since it has only been developed in the above forms 

 in connection with the larger nephridia and as a modification 

 of the original network, and has thus had its origin within the 

 Chsetopod group. W. Baldwin Spencer. 



Melbourne University, May 3. 



Strange Rise of Wells in Rainless Season. 

 My attention has "been directed to a letter published by you a 

 few weeks ago (May 31, p. 103) under the above heading. It 

 would appear that there is something mysterious in the eyes of 

 the author of the communication in question in the fact that the 

 water in two wells at Fareham rose several feet in the month of 

 March, as he states, "after a continuance of north-east wind, 

 without rain, but with half a gale blowing " ; so that it would 

 appear that there was some connection between the north- 

 easterly gale and the rise of the water. 



In this, however, the author is entirely mistaken ; the rise of 

 water in the wells in question is nothing more than the ordinary 

 seasonable rise due to percolation. For twelve years past I 

 have been carrying on constant observations of the underground 

 water-supplies in various parts of this country, and it is quite 

 true, as mentioned by the writer of the letter, that ordinarily the 

 water in wells rises in the winter and falls in the summer ; but 

 this is by no means an exceptional rule, for in the present season . 

 there have been two low waters, the last of which occurred in 

 the southern counties on the 8th of March in the present year. 

 After that date commenced a very wet period, and before the 

 end of the month over z\ inches of rain had absolutely passed 

 through the ground as measured by my percolation gauges. 

 The water in a well on the Surrey hills, which had been falling 

 up to March 8, rose before the end of the month over 30 feet, 

 which rise was entirely due to the replenishment from rainfall. 

 I may point out that there are many wells at the present time 

 in which the water is still rising, while in others in the same 

 districts the water is falling, for the simple reason that as a rule 

 underground water follows the same law as water flowing in a 

 river, and that the floods or high waters descend from the 

 highest to the lowest districts, so that at present in wells situated 

 in high positions the water is falling, while the crest of the wave 

 of high water in the same watershed has not yet been reached 

 in the lower levels of the district. 



That the water in wells does fluctuate under certain conditions 

 of the wind there is no doubt, as I have already drawn attention 

 both to the fluctuations which take place in the water-levels of 

 wells under barometric pressure and also in the volume of water 

 discharged from the ground with a fall of the barometer. It 

 should be noted that the rise of water in wells when due to 

 barometric changes coincides with the fall of the barometer. 

 Now a north-easterly wind as a rule is accompanied by a high 

 barometer, and therefore is not likely to influence the rise of 

 water in a well. During the month of March the rainfall was 

 above the average, while there were comparatively few days 

 with easterly winds, the only time when it could be termed 

 a half-gale from the north-east occurring on the 19th of March, 

 by which time the water in all the wells, had made a consider* 

 able rise, due simply to ordinary percolation. Thus there is no 

 mystery attaching to the rising of the water in these wells at 

 Fareham. The rise simply took place from the replenishment 

 of the springs, which this year occurred at a "period somewhat 

 different from ordinary years. Baldwin Latham. 



7 Westminster Chambers, Westminster, June 21. 



THE OPENING OF THE MARINE BIOLOGICAL 

 LABOR A TOR Y AT PL YMOUTH. 



THE Laboratory at Plymouth, which is now ready 

 -*- for work, is remarkable as being the first institution 

 in this country designed purely for scientific research 

 which has been originated and firmly established by the, 

 efforts of scientific men appealing to the generosity and 

 confidence of wealthy individuals and corporations who 

 desire the progress of knowledge for practical ends and 

 the general good of the community. 



It may be said that the Marine Biological Association 

 will begin its active career on and after Saturday next. 

 On that day Prof. Flower will, on behalf of the Associa- 

 tion, declare that the Laboratory at Plymouth, which is 

 now complete, is open for the purposes of biological 

 research. The opening of the Laboratory may be said 

 to mark an epoch in English zoological science, just as 

 the opening of the Stazione Zoologica at Naples, which 

 is essentially a German undertaking, marked an epoch in 

 German science. It is true that small sea-side labora- 

 tories have already been established in the United King- 

 dom — at Granton, St. Andrews, and Liverpool Bay ; but 

 none of them can compare with the present undertaking 

 in size and importance, and none can offer such advantages 

 to the investigator. 



The present institution, it may be remembered, is 

 historically the outcome of the International Fisheries 

 Exhibition held in London in 1883. That Exhibition 

 served partly as an amusement to Londoners, but it also 

 performed a far more important service — it directed 



