4o6 



NATURE 



{March 6, 1879 



overwhelmed, even when their lamps were burning freely. 

 These facts point to an entirely different mode of treating 

 those who have been rescued and who are still suffering 

 from the effects of after-damp, from that which has been 

 hitherto adopted. It is not too much to say that many 

 a life could have been saved if, acting on Hoppe-Seyler's 

 observations, artificial respiration could have been main- 

 tained for some time after apparent death. 



There is much in this book that we should have liked 

 to have dwelt upon had space permitted, for almost on 

 every page we discern evidences of originality and fresh- 

 ness such as might be expected from one who, as we have 

 seen, has brought the researching* spirit to bear upon his 

 subject. Whilst chemists are wearying themselves and 

 others with vain speculations as to bonds and atomic- 

 groupings, far too many of the common matters of every- 

 day life are thrown aside as unfruitful or worked out. No 

 one, however, could take up this book and not see that 

 in the matter upon which it treats there are fifty problems 

 waiting for solution — some of them most pressing in the 

 interests of humanity, and any one of them capable of 

 yielding a rich harvest of facts. T. E. Thorpe 



THE MORPHOLOGY OF THE ECHINODERMS 



Morphologische Studieti an EcJiinodermen. Von Dr. 

 Phil. Hubert Ludwig, Director der naturwissenschaft- 

 lichen Sammlungen in Bremen. i Band mit 23 

 Tafeln und 5 Holzschnitten. (Leipzig: Verlag von 

 Wilhelm Engelmann, 1877-79.) 



WITHIN the last three years very numerous re- 

 searches have been made on that most interest- 

 ing group, the Echinoderms, to which, we are glad to 

 see, the rank of a distinct sub -kingdom is now generally 

 assigned, Greeff, Gotte, Lange, Ludwig, Simroth, and 

 Teuscher, in Germany ; Perrier in France, Th^el and 

 Lov^n in Sweden, Agassiz, Lyman, and Pourtal^s in 

 America ; and in our own country Sir Wyville Thomson, 

 Duncan, Sladen, and the two Carpenters, father and son, 

 have each contributed more or less to our knowledge of 

 the morphology and physiology of the group. 



Of the many observations made and recorded by the 

 above-mentioned naturalists, those of Dr. Ludwig (" Ei- 

 bildung Ludwig," as we have heard him called by embryo- 

 logists) seem to us to be among the most important, alike 

 from theirvariety, and,aswe are strongly inclined tobelieve^ 

 from their general accuracy. We are not so sure, how- 

 ever, that all Dr. Ludwig's conclusions are as correct and 

 reliable as his observations are trustworthy, for there are 

 certain points on which we have very strong grounds for 

 dissenting from his views. 



The volume before us, representing the result of three 

 years' work, mostly microscopic, is the first of a promised 

 series of studies in Echinoderm morphology, and consists 

 principally of memoirs on the anatomy of Crinoids and 

 Starfishes. 



It contains much that is new, or rather that was so 

 when the individual memoirs were first published in the 

 Zeitschrift fiir ivissenschaftliche Zoologie, and much that 

 is to be found, stated more or less correctly in the 

 ■writings of other workers, _both before Ludwig and 

 contemporaneous with him. 

 The first paper in the series, forming about one-third 



of the whole volume, is devoted to the anatomy of 

 Comatula. While generally confirming Dr. Carpenter' s 

 results, respecting the canals of the arms and the 

 chambered organ, Ludwig (whose observations on this 

 type were contemporaneous with those of four other 

 observers, two in Germany and two in this country) 

 publishes several new and interesting anatomical details. 

 Among the most important of these is the presence of 

 blood-spaces around the genital organs, and also of a 

 system of blood-canals ventral to the water-vascular 

 system. Both of these systems probably communicate 

 with the vascular " axial prolongation " of Dr. Carpenter, 

 which runs up into the disc from the chambered organ 

 situated in the calyx, and represents the " heart " of the 

 Starfishes. 



Ventral to the radial blood-canal is the fibrillar sub- 

 epithelial band, to which Dr. Ludwig assigns a nervous 

 character from its resembUnce to a similar and similarly 

 placed structure, that is generally, though not universally, 

 supposed to be the nerve of the arm of a Starfish. 



Ludwig's views have been completely adopted by 

 Gegenbaur, in spite of the fact that this band is absent 

 from half, or sometimes from more than half, the arms of 

 many Comatulae. We scarcely think that Ludwig has 

 taken this fact sufficiently into consideration in his discus- 

 sion of Dr. Carpenter's suggestion that the axial cords 

 of the skeleton constitute the chief nervous system of 

 Comatula ; and we are not altogether satisfied with the 

 purely diagrammatic manner in which he figures this 

 axial cord, and with the meagre description which he 

 gives of it. He makes no mention whatever of the regu- 

 lar manner in which it gives off branching bundles of 

 fibres to the muscles and other structures in the middle 

 of every arm-joint, except ^in quoting their discovery by 

 others, though he cannot well have helped seeing them, 

 and he does not deny their existence. At the same time 

 he seems inclined to admit the probative force of Dr. 

 Carpenter' s experiments at Naples, which tend to show 

 that these axial cords are the motor nerves, at any rate of 

 the complex Crinoid organisation, permeated though they 

 may be by a coagulable fluid. Should this view be the 

 true one, it is another argument in favour of Leuckart's 

 separation of the Crinoids and their aUies from the other 

 Echinoderms, to form a distinct class, the Pelmatozoa. 



Until lately the Crinoids have not been credited with an 

 ambulacral system homologous with that of the other 

 Echinoderms. Gotte, however, has shown that, as far as 

 development is concerned, this is not the case, and the 

 true water-vascular ring of the adult Comatula was first 

 described by Ludwig, though its radial branches in the 

 arms have long been known. Depending from it into 

 the ccelom are numerous small tubules which Ludwig 

 describes as open at the ends, and compares to the sand- 

 canals of the other Echinoderms, more especially of th 

 Holothurians. 



After finishing his researches on the anatomy of Coma- 

 tula, Ludwig turned his attention to Rhizocrinus, and 

 found that it corresponds with Comatula in all essential 

 points of structure. This was the first stalked Crinoid in 

 which the presence of a chambered organ was deterr 

 mined. It has since been found in Pentacrinus and 

 Bathycrinus, and Ludwig's discovery that its chamber 

 are continued down the axis of the stem as five blooi 



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