December" 8, 192 1] 



NatcM^ 



45^) 



undeserved slur on an honourable and useful call- 

 ing. 



It is quite rational that many pharmacists should 

 xhibit reluctance to part with a title which they 

 ave legally held since the Act of 1851, and one 

 allowed by the fact that some of the early 

 'hemists — for example, Scheele — were practising 

 pharmacists. In the course of years, however, 

 and following the necessary classification of innu- 

 merable chemical observations in a distinct branch 

 of scientific knowledge, the extension of chemistry 

 has passed almost entirely from pharmacists, who 

 are thus designated by a misnomer. It is the 

 purpose of the Pharmacy Acts Amendment Bill to 

 rectify this irregularity as from the first day of 

 January, 1925. 



In view of the laudable object of the Bill and 

 the support which the principle at least might 

 he expected to receive from chemists, it is diffi- 

 It to understand the action of the promoters in 

 holding themselves aloof from the Institute of 

 Chemistry, and not even consulting the council of 

 that body. Consequent on this omission, the 

 official attitude of the Institute has now been set 

 forth in a letter from the registrar to the pro- 

 moters stating that the council would welcome 

 any legislation tending to remove the present con- 

 fusion, which it deplores; but it dissociates 

 itself from the suggestion that it should 

 be represented on the central council, which, as 

 proposed in the Bill, would be concerned with the 

 pharmaceutical register. This attitude will be 

 approved alike by pharmacists and by chemists, 

 for the latter have not the slightest claim to par- 

 ticipate in the registration of pharmacists ; 

 chemists have never suggested, or even contem- 

 plated, an action which pharmacists justifiablv 

 would resent as an interference with their own 

 functions. 



Echinoderm Larvae and their Bearing- on 

 Classification. 



Studies of the Development and Larval Forms of 

 Echinoderms. By Dr. Th. Mortensen. Pp. iv + 

 261 + 33 plates. (Copenhagen: G. E. C. Gad, 

 May, 192 1.) 2I. 25. 



THE development of Echinoderms from the 

 ^gg presents one of the most striking of 

 life processes known to us. The changes through 

 which the individual passes are even more remark- 

 able than those accompanying the more familiar 

 metamorphosis of a caterpillar into a butterfly. 

 The egg develops directly into a free-swimming 



NO. 2;iq, VOL. 108] 



larva of bilateral structure, adapted in most 

 cases for pelagic life ; within this larva there is 

 gradually formed a body with radial structure and 

 special organs, which, being set free from the 

 larva, grows into the adult sea-urchin, starfish, 

 crinoid, or holothurian — an adult rarely free-float- 

 ing and generally abiding in one place. It is 

 almost as though there were an alternation of 

 generations, as though the larva bore the young 

 echinoderm as a mother bears a child ; and this 

 idea, though not really justified, is forcibly re- 

 called by Dr. Mortensen's account of an ophiurid 

 larva, which, after dropping the young brittle- 

 star, proceeds to reconstitute its own body, and 

 continues life as an independent individual. Dr. 

 Mortensen even suggests, rather audaciously, that 

 it may repeat the metamorphosis. 



It is with those larvae that are adapted to a 

 pelagic life that Dr. Mortensen is mainly con- 

 cerned. The adaptation consists largely in the 

 development of long rod-like processes, generally 

 known as arms, although they have nothing to do 

 with any structures so called in adult echinoderms. 

 These processes serve as balancers and aid th^ 

 flotation of the tiny creature. In only a few forms, 

 however, do the skeletal rods support any paddle- 

 shaped expansion of the soft tissues, and in only 

 one, here first made known by Dr. Mortensen, 

 can they be moved like oars by means of special 

 muscles. 



The absolute distinction between the larva and 

 the adult, combined with the. difference of habitat 

 and the difficulty of raising all the stages in an 

 aquarium, has long hindered the attempt to assign 

 the various larvae to their respective species. They 

 have, therefore, for practical convenience, been 

 classified and named on an independent system. 

 In the present work Dr. Mortensen's chief airn 

 has been to decide how far this classification 

 agrees with that of the adults, or, to put the 

 matter in another way, how far the differendes 

 and resemblances of the larvaa throw light on the 

 affinities of the adult genera and species. Previ- 

 ously the pelagic larva? of about seventy various 

 echinoderms had been identified, and Dr. Morten- 

 sen here describes the development of fifty-five 

 forms previously unknown. The data, therefore, 

 though relatively very few, are enough to warrant 

 a discussion of the problem. 



In so many instances do the lar\ae of closely 

 related species resemble one another, so often do 

 the larvae of allied genera agree in important char- 

 acters, so distinct are the lar\-al forms of the 

 several orders no less than of the classes, that Dr. 

 Mortensen is justified in his conclusion that simi- 

 larity of larval structure implies the relationship 

 of the respective adults. The converse proposi- 



