ON THE BRITISH ANNELIDA. 251 



ova. In this indirect sense, and that alone, can the "spontaneous division" 

 of the body in the Annelid be regarded as participating in the reproductive 

 operations. 



All that is known of the embryology of the Annelida has been within re- 

 cent years only contributed by Milne-Edwards. The illustrations given by 

 hira delineate the successive stages presented by the young of Terebella 

 nebulosa in the process of growth. As the author of this Report has yet 

 enjoyed few opportunities of studying the development of the young, he pro- 

 poses for the present to omit entirely that department of his subject, hoping 

 that on some future occasion he shall be able to complete the history of the 

 British Annelids by the addition, to the embryology of the worms, of the 

 results of his own personal inquiries. Nothing would be here gained by 

 the further repetition of the oft-repeated descriptions of Duges with reference 

 to the structure of the generative organs of the Leech and the Naid. It is 

 remarkable to relate, that no anatomist, from the epochs of Duges and Sir 

 Everard Home to the present time, has perceived that these descriptions 

 comprise only one-half of the sexual organs of these worms. It is extraor- 

 dinaiy that none could discover the physiological necessity, even in herma- 

 phrodite organisms, for a feminine system, for some ovarian apparatus. These 

 descriptions relate only, and that not by any means accurately, to the mascu- 

 line elements. 



It will be afterwards proved that every anatomist who has ever investigated 

 the organization of the Annelida, has mistaken the true utricular ovaria for 

 the respiratory sacculi. If the ultimate structure of these so-called sacculi 

 had at any time been made the subject of minute examination, their real 

 nature as the female generative system could not have eluded the eye. 

 M. Quatrefages, whose figures have been copied into the last and best edition 

 (Crochard's) of the ' Regne Animal,' described these ovarian sacculi as " les 

 poches secretrices venant s'ouvrir sur le dos par les canaux renflis." The 

 same author figures in the same great work the corresponding organs of the 

 Leech, and speaks of them as "les poches secretrices laterales avec leur 

 caecum." Both the figures and the description prove that M. Quatrefages 

 could not have attained to the remotest conception of the true significance 

 of these organs. Nor do the figures given in the 'Regne Animal,' costly 

 and beautiful as they are as works of art, convey any but the most egre- 

 giously erroneous view of the structure and anatomical relations of these 

 organs. All observers are liable to error, but the errors of distinguished 

 men, at once ornaments and authorities in the walks to which their genius 

 may have been dedicated, are mischievous in proportion to the height from 

 which they descend, and should be combated at once with unmeasured 

 strength of language. Numerous examples might be quoted from every 

 branch of science, of the pernicious influence which an undue reverence for 

 authority has exercised on the progress of knowledge. In no department of 

 observational science has hereditary error grown so venerable by repetition 

 as in that which embraces the Annelidan division of comparative anatomy. 



The title of the author of this Report to the merit of having added some- 

 thing new to the traditionary lore transmitted through a long succession of 

 systematic writers, can only be determined by a comparison of his descrip- 

 tions and figures with those given in the works of the best and most recent 

 writers. In the succeeding account he is desirous to describe minutely and 

 at length the results of his own investigations. This will prove more accept- 

 able to science than the repetition of that which has already been so often 

 repeated. The dissection of the reproductive organs in these animals is 

 attended by^ many practical difficulties ; it has therefore proved impossible 



