ZOOLOGY. 347 



trerne depths ; and that it should have been almost unanimously 

 recognized as an axiom, that at a depth of four hundred, or at most 

 five hundred fathoms, life, whether animal or vegetable, must be 

 extinct. The fact is unquestionable, that, as we descend beyond the 

 first hundred fathoms, the traces of life become more and more re- 

 mote ; and it is probably owing to this gradual diminution in the num- 

 ber of animal forms, as the depth exceeds this limit, that it has been 

 assumed, rather as a matter of theory than of observation, that a 

 point is speedily reached at which all the conditions essential to life 

 are extinguished. This view has also derived support from the idea 

 that " animal life depends on the previous existence of vegetable life." 

 In the case of the higher orders of the animal kingdom, the law no 

 doubt holds good. Not so, however, in the case of the lower. The 

 conditions essential to the perpetuation of the one are not essential 

 to the perpetuation of the other. Thus, light is indispensable for the 

 healthy respiration and growth of the vegetable. The animal can, 

 on the other hand, respire as freely in the blackest darkness as in the 

 broad glare of day. And this is no doubt the reason why vegetable 

 life in the ocean attains its final limit in depth so much sooner than 

 animal life. 



The Foraminifera are the organisms to which reference has been 

 made as performing so very important a part in the formation of cer- 

 tain strata on the earth's crust. They occur abundantly in all exist- 

 ing seas, and in almost all marine sedimentary strata, as chalk, lime- 

 stones, etc. In the mud " irooze," which is brought up from great 

 depths in many parts of the ocean, immense numbers of Foraminifera 

 are to be met with, chiefly belonging to one species. The question 

 as to their occurrence in a living or dead state, however, was over- 

 looked or undecided. Most authorities who have written on the sub- 

 ject are of the opinion that they do not live at great depths, but that 

 their shells and remains have drifted to the positions in which they 

 were found from shallower waters, or have subsided from the upper 

 strata of the ocean. Professor Huxley was one of the very few who 

 leaned to the more correct opinion ; he having declared that, although 

 far from regarding it as proved that the Globigerina (the species re- 

 ferred to) live at these depths, the balance of probabilities seemed 

 to him to incline in that direction. 



The difficulty is, how to determine the point conclusively ; for it 

 seems legitimate to infer that, if these organisms are specially 

 adapted to exist under conditions differing so widely from those pres- 

 ent at or near the surface, the very circumstance of removing them 

 from one set of conditions to the other would inevitably destroy their 

 vitality, and perhaps their normal structure, before it could become 

 practicable to subject them to microscopic analysis. Nor is the diffi- 

 culty an imaginary one. For, taking into consideration the entirely 

 altered circumstances in which these creatures must find themselves 

 placed when brought to the surface, locomotion, or even the protru- 

 sion of their filamentary appendages, could hardly be expected. The 

 mere existence of the fleshy parts within their shells, and that too in 

 an apparently recent condition, affords no proof, inasmuch as the 

 great quantity of saline matter present in sea-water, and especially 



