26 



NATURE 



[May 



2, li 



to the serious student who wishes to consult original 

 authorities. 



In addition to this objection to the omission of 

 reference to authors, there is the fact that it suggests 

 (perhaps rightly, perhaps wrongly) that the author is 

 ignorant of the correct name with which to connect a 

 particular view or discovery, or that he is too lazy to 

 look the matter up, or that he wishes fraudulently to 

 give the impression that he makes such and such a 

 statement of his own knowledge and independently. 

 Finally there is the objection, that by the omission of 

 authors' and discoverers' names, and by thus failing to 

 pursue the historical method of exposition, a very great 

 means of lending interest to a vast mass of detail is 

 sacrificed. Not only is the student deprived of what is 

 often, when present, a very important aid to his memory, 

 but what is in many cases the best and simplest scheme 

 for the presentation of the subject to the student— viz. its 

 actual historical development — is rendered impossible. I 

 hope that others who feel as strongly as I do as to the 

 injury done by those zoologists who deliberately ignore 

 or refuse to cite the names and writings of their prede- 

 cessors and contemporaries, will join in taking steps to 

 condemn and, if possible, arrest, by the expression of 

 authoritative public opinion, what seems to me a mis- 

 chievous and mean kind of literary injustice. 



The omission of reference to authorities is no doubt to 

 some extent the cause of the existence in Parker's and 

 Haswell's " Text-book of Zoology " of mistakes which 

 either Prof. Haswell or Prof. W. N. Parker would have 

 seized upon and corrected had they appeared as un- 

 verified by reference to a recent author in an ordinary 

 treatise. But since no statement in the book is so sup- 

 ported, a reader revising the proof for the author would, on 

 seeing an extraordinary assertion, say to himself, " Dear 

 me ! I suppose that is something new ; something I've 

 missed." It is probably owing to this that blunders have 

 been left to mislead the student, and to undermine our 

 confidence in all the statements made in the book which 

 have any appearance of novelty. I have not searched 

 the "Text-book" for errors, but I have come across the 

 following in " sampling " its pages. Many of them are 

 so serious that they should certainly be corrected in a 

 new edition with the least possible delay, and steps 

 should be taken to ascertain whether others of a like 

 kind exist, and if so to remove them. 



The most astonishing of these errors is the assertion 

 by two sons of W. Kitchen Parker, that ossification 

 occurs in the Selachii. They say (vol. ii. p. 158) : 



" The skeleton is composed of cartilage with, in many 

 cases, deposition of bony matter in special places — 

 notably in the jaws and the vertebral column. The entire 

 spinal column may be nearly completely cartilaginous 

 (Hexanchus and Heptanchus), but usually the centra are 

 strengthened by radiating or concentric lamelte of bone ; 

 or they may be completely ossified." 



On the other hand (an inconsistency due probably to 

 duplicate authorship and multiple responsibility) we find 

 in the description of Chiloscyllium on p. 136, the statement 

 that the skeleton is composed entirely of cartilage with, 

 in certain places, depositions of calcareous salts. And, 

 moreover, in the histological introduction in the first 

 volume " calcified cartilage " is very properly mentioned 

 NO. 1489, VOL. 58] 



and distinguished from bone. In attempting to follow 

 up this extraordinary blunder, viz. the assertion that 

 ossification takes place in the cartilage of Selachii, I 

 have looked into the translation of Wiedersheim's 

 " Comparative Anatomy of Vertebrates," and there 

 I find the same assertion, the word which in the 

 original German is "Verkalkung" being translated 

 " ossification " (as though the German had been 

 " Verknocherung "). Now the translator who made this 

 mistake is Prof. W. N. Parker, of Cardiff. Hence we 

 may conclude that it is he who is responsible for the 

 similar statement in the " Text-book," and not either the 

 latejeffery Parker nor Prof. Haswell of Sydney. But whose 

 soever the fault may be, the sooner so grossly misleading 

 a statement is removed from a book addressed to young 

 students, the better. 



The following erroneous statements occur in vol. i. 

 On p. 423 we read : 



" Externally each nephridium [of the earthworm] 

 opens by one of the small excretory pores which have 

 already been mentioned as occurring on the ventral sur- 

 face ; internally it ends in a funnel-shaped ciliated 

 extremity with an aperture, the nephrostome, opening into 

 the cavity of the corresponding segment." 



As a matter of fact, it is a curious and characteristic 

 thing that the nephridia of ChcCtopoda do not open into 

 the segment corresponding to the external pore, but into 

 the segment next in front of it. 



P. 372. In the description of Holothuria, our authors 

 state : 



" Opening into the cloaca is a pair of remarkable 



organs of doubtful function, the so-called respiratory 



trees. . . . Each of the terminal branches ends in a 

 ciliated funnel opening into the coelome." 



As a matter of fact, the Holothurian respiratory tree 

 does not possess such ciliated funnels, and in this differs 

 notably from the so-called "posterior nephridia" of the 

 Echiurids. 



P. 561. In the description of Peripatus we read : 



" A layer of coelomic epithelium lines the wall of the 

 coelome and invests the contained organs. Incomplete 

 muscular partitions divide the cavity into a median and 

 two lateral compartments." 



Nevertheless the authors elsewhere recognise the fact 

 demonstrated by Sedgwick and myself, that the blood- 

 holding body-cavity of Arthropods is not the ccelom 

 but an enlarged system of blood-sinuses the hasmocoel ; 

 whilst the coelom is reduced to perigonadial and peri- 

 nephridial rudiments. 



P. 732. We read that in Nautilus 



" A large vena cava occupies a position corresponding 

 closely with that of Sepia. It presents the remarkable 

 peculiarity of being in free communication by numerous 

 (valvular) apertures with the viscero-pericardial cavity of 

 the coelome." 



A remarkable peculiarity, indeed, and one which has 

 no existence in fact ! The vena cava communicates with 

 veinous blood-spaces by those apertures, and not with 

 the coelom. 



In addition to such down-right errors as the above, it 

 must be noted that the authors have too readily accepted 

 the statements of some writers whose names, however, as 

 usual, they do not give. Thus they describe and figure^ 



