!8o 



NATURE 



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specimens of one genus at Fort Wool, and the same genus — ■ 

 Lucifer — in great abundance at Beaufort, associated with another 

 genus which is also new to North America. As nothing what- 

 ever was kuown of the development of Lucifer, we made every 

 effort to obtain the eggs andyung, and after four months of 

 almost fruitless labour we finally .succeeded in finding all the 

 stages of the nietauiorphosis, and figured them in a complete 

 series of ninety-nine drawings. We alo obtained a somewhat 

 le«s complete series of figures of stages in the life history of the 

 second Sergestid. Our only motive in this work was the desire to 

 fill a gap in our knowledge of crustacean development by supplying 

 the life-history of a very interesting group of animals, but the 

 result was found to have a vei-y unexpected value, since it 

 contributes to the discussion of a number of problems in general 

 embryology and morphology, and is the most significant crus- 

 tacean life history which has ever been studied. 



"The following are some of the more important points : — 

 The egg undergoes total regular se,'mentation. There is no 

 food-yolk, and cleavage goes quite through the egg. There is a 

 true segmentation cavity. Segmentation is rhythmical. There 

 is an invaginate gastrula. The larva leaves the egg as a Nauplius, 

 and passes through a protozoea stage and a schizopod stage. 

 The fifth thoracic segments and appendages are entirely wanting 

 at all stages of development. 



" Another interestin'^ i;roup which was studied is the Porcel- 

 lanidce ; the least specialised of the true crabs. The adults of 

 our American species are almost restricted to our southern 

 waters, although the swimming larvre are carried north by the 

 Gulf Stream. Within the last two years two northern natu- 

 ralists have studied these floating embryos upon the south coast 

 of New England, but as they were working upon straggler-- si 

 far from home, their accounts are inc implete and somewhat 

 contradictory. Our advantages at Beaufort enabled us to con- 

 tribute towards the solution of this confused subject by raising 

 one species of Forcellana from the egg. We also raised six 

 other species of crabs from the egg, and made drawings of the 

 more important stages of development. One of the species 

 which was thus studied is the edible crab. Its metamorphosis 

 has never been figured, and although it presents no unusual 

 features, its economic importance gives value to exact knowledge 

 of its life history. Mr. Wilson also studied the development of 

 one s: ecies of Pycnogonida, a group of very peculiar Arthro- 

 pods distantly related to the spiders. As he has paid especi.al 

 attention to the systematic study of this group, and is now 

 engaged in describing the Pycnogonids collec'ed in the Gulf 

 Stream by Mr. Agassiz, the opportunity to study them alive in 

 the laboratory has been a great advantage to him. 



"Another important investigation is the study by Mr. Wilson 

 of the embiyology of the marine Annelids. Although the 

 representatives of this large group are abundant and widely dis- 

 tributed, little was known of the early stages of their develop- 

 ment until he procured the eggs of several species and studied 

 them at Beaufort. This investigation has shown, among other 

 things, that the accepted division of Annelids into two great 

 groups, the 01igocha:;ta and Folychieta, is not a natural method 

 of classification. The work upon the development of marine 

 Annelids was supplementary to an investigation which Mr, 

 Wilson carried on last spring at Baltimore, and which he will 

 continue this winter, upon the development of land- and fresh- 

 water Annelids. 



" As much time as po-sible was given this sea.son to the study 

 of the hydroids and jelly-fish of Beaufort. The life history of 

 several of them were investig.nted, a thorough anatomical study 

 of some of the most important forms was carried on, and nearly 

 two hundred drawings was made. It is almost impossible to 

 complete a study of this kind in a single season, but if one or 

 two more summers cau be given to the work, we have every 

 reasori to hope for valuable results, f ir although the North 

 Carolina coast is the home of many species which are only 

 found as stragglers upon our northern coa-t, and of other species 

 which are not known to occur anywhere else, and of some 

 genera and families which are new to the North American coast, 

 this field has suffered almost total neglect. 



" Nearly three months of the time of two members of our 

 party, Mitsukm-i and Wilson, were given to the study of the 

 habits, anatomy, and development of Kenilla, a compound 

 Polyp very much like that which forms the precious coral, but 

 soft and without a stony skeleton. The animals which form the 

 community are so intimately bound together that the community 

 as a whole has a well-marked individuality distinct from that of 



the separate animals which compose it. The compound indi- 

 viduality of ReniUa is quite rudimentary as comp.ared with that 

 of a Siphonophore, and as there is no trace of it in the closely 

 allied Gorgonias, it furnishes an excellent field for studying the 

 incipient stages in the formation of a compound organism by the 

 union and specialisation of a community of independent simple 

 organisms. With this end in view the anatomy of the fully- 

 developed community was carefully studied, and the formation 

 of a community was traced by rearing a simple solitary embryo 

 in an aquarium until a perfect community had been developed 

 from it by budding. During the process of development the 

 law of growth by which the characteristics of the compound 

 organism are brought about was very clearly exhibited, and it is 

 fully illustrated by nearly one hundred drawings. 



" One of the most interesting results of our work is the 

 explanation by Mr. Wilson of the origin of the metamorphosis of 

 the larva of Phoronis, a small Gephyrean worm which lives in a 

 tube. Several <if the most noted embryologists of Europe have 

 studied the development of Phoronis, and our knowledge of its 

 life history is due to their combined labours. Last summer Mr. 

 Wilson reviewed the subject, and added some important points, 

 and during the present season he has shown by the comparison 

 of a great number of allied forms that the very peculiar meta- 

 morphosis admits of an extremely simple explanation. The 

 adult is sedentary and confined to its sand tube, while the larva 

 is a swimming animal totally different in structure. The change 

 from the larva to the adult is very rapid and violent. It occupies 

 only a few minutes, and during the change the larva becomes 

 turned wrong side out, so that what was internal is external. 

 Mr. Wilson's comparison shows that Phoronis was originally a 

 free animal, and that the structural peculiarities which fit the 

 adult for .sedentary life in a tube are of recent acquisition. The 

 larva has however retained its ancestral adaptation to a swimming 

 life in order to provide for the distribution of the species. T here 

 must have been a time, in the evolution of the species, when the 

 adult was imperfectly adapted to a sedentary life, and also im- 

 perfectly adapted to a swimming life ; and if the development 

 of the individual were a perfect recapitulation of all the stages in 

 the evolution of the species, we .should have, between the 

 swimming larva and the sedentary adult, a stage of development 

 during which the adaptation is not quite perfect for either mode 

 of life. It is clearly an advantage for the animal to pass through 

 this stage .is quickly as pissible, or to escape it altogether. The 

 peculiar metamorphosis enables the larva to remain perfectly 

 adapted to a locomotor life until the occurrence of the sudden 

 change which fits it for life in a tube ; and Mr. Wilson has 

 pointed out the manner in which the metamorphosis has been 

 acquired in order to bridge over the period of imperfect 

 specialisation. This explanation is somewhat similar to that 

 which Lubbock has given of the origin of the metamorphosis of 

 insects, and we may hope that the same method of investigation 

 will throw light upon the significance of other remarkable 

 instances of metamorphosis in the invertebrates. 



" During the summer the following abstracts of some of the 

 more important points in our work have been published in 

 scientific journals : — 



The Development of the Cephalopoda and the Homology of 

 the Cephalopod Foot. By W. K. Brocks. Amer. Journal of 

 Set, nee. 



The Development of Annelids. By E. B. Wilson. Amer. 

 Journal of Scicnee. 



The Rhythmical Nature of Segmentation. By W. K. Brcoks. 

 A mer. Journal of Science. 



The Origin of the Metamorphosis of Actinotrocha. By E. 

 B. Wilson. Amer. Assoc, Boston Meeting. 



Notes on the Medusas of Beaufort. By W. K. Brooks. Amer. 

 Assoc, Boston Meeting. 



Budding in Free Medusre. By W. K. Brooks. Amer. NtU. 



Development of Marine Polychxtous Annelids. By E. B. 

 Wilson. ZodlogischerA nzeiger. 



Embryology and Metamorphosis of Lucifei'. By W. K. 

 Brooks. Zoologischer Anzei^er. 



The Early Stages of ReniUa. By E. B. Wilson. Amtr. 

 Journal of Science. 



" Other abstracts are now in the press, and others ai-e ready 

 fir publication. 



"A paper, with four plates, on the 'Early Stages of the 

 Squid,' is .also in the press, and will soon be issued in the 

 Memorial Volume of Memoirs of the Boston Society of Natural 

 History." 



