8o6 



NA TURE 



[December 16, 192: 



Letters to the Editor. 



[77/!* Editor does not //old himself responsible for 

 opinions expressed by his correspotidents. Neither 

 can he undertake to return, or to correspond with 

 the zeriters of, rejected manuscripts intended fo) 

 tins or any other part of Nature. No notice is 

 taken of anonymous communications.^ 



F.chinoderm Larvae and their Bearing on 

 Classification. 



[n Nature of December 22, 1921, Prof. E. VV. 

 Vlai Bride, in consequence of Dr. F. A. Bather's 

 review (in Nature of December 8, 1921) of my work, 



Studies of the Development and Larval Fornix of 

 Kchinoderms," has taken the opportunity of making 

 some remarks which, at least partly, have somewhat 

 the character of a personal attack on me. Being at 

 that time on a scientific expedition to the Malay 

 Archipelago, it was not until the middle of May last 

 that I received the issue of Nature containing that 

 communication. In spite of Dr. Bather's chivalrous 

 defence on my behalf, I think it desirable to send to 

 Nature an answer to Prof. MacBride's letter. Tins 

 could not possibly be done then, however, as out there 

 (at the Kei Islands) I had no access whatever to 

 literature — not even to my own work. I had to 

 wait until my return from the expedition, and there- 

 fore it is only now that I am in a position to send a 

 reply to the statements made by Prof. MacBride a 

 5 eai ago. 



Prof. MacBride first emphatically objects to the 

 idea that the metamorphosis of Echinoderms might 

 be an alternation of generations. It is not quite 

 clear to me whether this is addressed to the reviewer 

 or to the author, or perhaps to both of us. Dr. 

 Bather has replied for himself to this objection. 1 

 may be allowed here to reply to it for my part, and 

 shall do so simply by quoting what I did write. 



On p. 124 of my work I state that in Ophioplutt u 

 opulentus the postero-lateral arms remain in connexion 

 after the young Ophiuran has been dropped, in the 

 same way as it occurs in the larva of Ophiothru 

 fragilis. In Ophiopluteus opulentus, however, it 

 appears that the larva does not perish after a little 

 while, as doubtless happens to the Ophiothrix-larva. 

 Some specimens show that a new larval body h 

 to regenerate from the postero-lateral arms. That we 

 have liere to do not simply with abnormal larva 

 evident from the fact that the long postero-lateral 

 arms are perfectly normally developed, which could 

 not be the case in an abnormal larva with the mouth 

 and intestinal organs imperfectly developed, and 

 accordingly unable to feed. Further, on p. 148 is 

 said : " How far the process of regeneration goes 

 cannot be ascertained ; but in any case PL XX. 

 Fig. 5 shows that it may go on so far as till the 

 formation of a new mouth and oesophagus. It is 

 also evident from the numerous nuclei seen in the 

 anterior part of the new body that a vigorous growth 

 is going on here, so that it would seem most probable 

 that the process maj continue the short while, until 

 the new digestive organs are able to assume normal 

 function — and then there seems to be no reason to 

 doubt that a new complete and ultimately null 

 morphosing larva may be the result. Thus we wo lid 

 here have a trut ca 1 oj metagenesis, otherwise tot [L5 

 unknown in Echinoderms." Finally, on p. 1 pi I 

 11I; "in course, 1 do not mean to maintain 

 that definite proof of this astonishing regeneration 

 1 given. But the available material certain!) 

 indicates that it does take place. The problem most 

 urgently invites 1 loser investigation." 



1 think it clear from these quotations that I do not 



NO. 2772, VOL. I IO] 



characterise the metamorphosis of Echinoderms as an 

 alternation of generations. On the other hand, if 

 the regenerating larva goes on to metamorphose a 

 second tune, even Prof. MacBride certainly will have 

 i this as a (of course quite exceptional) case 

 ol metagenesis in Echinoderms. The correctness of 

 \ ations is not to be doubted — the regenerat- 

 ing lai 1 as are at the disposal of any one who ma-j \\ ish 

 io control my figures; and my conclusions, which 

 are perfectly logical, I cannot agree to be audacious. 

 In my statement that since the larvae of the more 

 primitive Asteroids (the Phanerozonia) are devoid of 

 a Brachiolaria stage, the sucking disk found in the 

 larvae of Spinulosa and Forcipulata must be a later 

 acquired specialised structure, and accordingly the 

 homology generally supposed to exist between the 

 sucking disk of the Brachiolaria and the Pelmatozoan 

 stalk only apparent, and the great part it has played 

 in phvlogenetic speculations unjustified, Prof. 

 MacBride most emphatically objects : " Xo more 

 rash statement could be made nor one more devoid 

 of foundation. Modern Asteroids are divided into 

 five groups, viz. Forcipulata, Valvata, Velata, Paxil- 

 losa, and Spinulosa. Nothing whatever is known of 

 the development of any valvate or velate form, but 

 the fixed stage is found not only in the development 

 of the Forcipulata (which Dr. Mortensen arbitrarily 

 regards as the most specialised forms) but also in the 

 development of the Spinulosa (which # all admit to be 

 the most primitive group). In the Paxillosa, which 

 include the British genera Astropecten and Luidia, 

 and which, mirabile dictu, Dr. Mortensen appears 

 to regard as primitive forms, the fixed stage is 

 omitted. . . ." 



I shall leave the strong expressions to Prof. 

 MacBride and only comment upon his statement that 

 " all admit " the Spinulosa to be the most primitive 

 group of Asteroids. 



Prof. MacBride will probably agree that among 

 naturalists now living the following are the first 

 authorities on Asteroids : W. K. Fisher, H. L. Clark, 

 K Koehler, and L. Doderlein. I have written to all 

 of them, asking them to tell me (1) whether they have 

 ever stated as their opinion that the Spinulosa are 

 the most primitive Asteroids (I did not remember 

 c\ er having met with such statements in their 

 publications, but I might, of course, have been mis- 

 taken) ; (2) to inform me which group of starfishes 

 they regard as the most primitive. All answered that 

 they had never stated the Spinulosa to be the most 

 primitive Asteroids. Prof. W. K. Fisher writes I 



think that the typical Phanerozonia such as the 

 Astropectinidaj, Odontasteridas, etc., are decidedly 

 more primitive than the Spinulosa, meaning by that 

 the Asterinida?, Echinasteridae, and Solasteridae, to 

 mention three of the families." Dr. H. L. Clark 

 writes that he agrees perfectly with me " in consider- 

 ing the Asteropectinidae as essentially primitive, ami 

 tin Spinulosa specialised." Prof. Koehler writes : 

 " Je crois, comme vous, que les types les plus primitifs 

 doivent etre cherches dans les formes voisines des 

 Astropectinidees, telles que le genre Hudsonaster et 

 d'autres genres tres anciens." Prof. Doderlein writes 

 that he regards the family Asterinida as " die 

 ursprflnglichste aller Seestern-Familien." Among 

 recent authorities on Asteroids, Doderlein thus is the 

 only one who holds a similar vievv as to the 1 lassifica- 

 tion of Asteroids as Prof. MacBride ; but as he has 

 never stated this opinion in any of his publications, 

 neither Prof. MacBride no: I could possibly know 

 anything thereof. 



I may further mention that both Sladen and 

 Ludwig, who, Prof. MacBride will probably agree, 

 must also count as authorities on asteroid classifica- 

 tion, likewise regard the Phanerozonia, not the 



