82 DE. G. H. FOWLEE—BISCATAN PLANKTON : 



waters of the Atlantic " — is, to my belief, absolutely deceptive, and must be attributed to 

 the faulty method of capture employed and to the consequently inadequate evidence laid 

 before him. In the first jAace, if one may argue from his diagram *, no hauls were taken, 

 at depths between 50 and 200 fathoms. Now, as has been shown above, this includes 

 the most populous zone in the ocean, and is well known to be so from the results of other 

 expeditions. Apparently it was entirely passed over in these collections. In the second 

 place, the species not having been identified, the deduction entirely neglects the fact that 

 diff'erent species inhabit different depths. Lastly, the conclusion takes no count of the 

 weakness of the method of serial open tow-nets at great depths — namely, that it does not 

 eliminate the organisms captured in the upward journey at higher levels : this alone is 

 enough to vitiate the conclusion. The effect of the upward journey through what 

 (according to my results) are more populous zones can to some extent be gauged from 

 the following observations : — My average specimens between 1250-1000 fathoms were 

 0"4 ; now hauls 27 a and 27 a' missed fire, and the closing-net failed to close, its contents 

 therefore represent specimens obtained on the upward journey only. These two hauls 

 contained no less than 39 sjiecimens belonging to six species ; ten specimens belonged 

 to serratodentata and fuvQata, of which I w^as unable to prove the occurrence below 

 200 fathoms by the closing-net ! 



The closing-net brings comparatively little to the surface, but of this little we at least 

 know accurately where it was caught f ; and when my curve of " all species together " 

 is compared with Mr. Gunther's result, there can be little doubt that a large proportion 

 of his specimens were caught on the upward journey. 



"With Mr. Giinther's second conclusion — that small specimens are more plentiful at the 

 higher levels, large specimens are more characteristic of greater depths — I am in entire 

 agreement, although I fear we might not agree exactly as to levels. But, so far as my 

 results go, tliis follow^s from the presence at higher levels of young specimens which seek 

 deeper water when adult (compare pp. 68 and 76). 



The only other attempts to record the vertical distribution of Chsetognathaas yet have 

 been made by Strodtmann and Steinhaus on the materials of the ' National ' (German 

 Plankton) Expedition. Unfortunately the results of the surface and horizontal hauls 

 have not yet been published ; only vertical and closing nets are available, and these only 

 for parts of the cruise. It is, therefore, of no value at present to compare the results of 

 the ' National ' and ' Research ' in detail ; in so far as they overlap, they agree in the 

 main, except in that the ' National ' failed to prove the existence of Chsetognaths below 

 1500 m. (812 fms.). 



Summary of the observed Distribution. 

 These conclusions are stated less dogmatically in the foregoing text : a reference to 



* No detailed list of the hauls oa this cruise has been published. Since the above was in print, I learn through 

 Mr. V. H. Blackman that two hauls were made between the depths mentioned. 



t By disoounecting port and starboard engines, and using them separately as required, we were able to keep the 

 ■wire rope straight up and down : Mr. George Murray's criticism of the uncertainty of the horizon therefore falls 

 (Joum. E. Geog. Soc. siii. p. 153). 



