90 EXPEDITION OF THE " CHALLENGER " m 



those which are found at the bottom, but I confess 

 that I doubt the accuracy of this statement. 

 Again, the occurrence of minute Globigerince in all 

 stages of development, at the greatest depths, is 

 brought forward as evidence that they live in situ. 

 But considering the extent to which the surface 

 organisms are devoured, without discrimination of 

 young and old, by Salpce and the like, it is not 

 wonderful that shells of all ages should be among 

 the rejectamenta. Nor can the presence of the 

 soft parts of the body in the shells which form 

 the Globigerina ooze, and the fact, if it be one, 

 that animals living at the bottom use them as 

 food, be considered as conclusive evidence that 

 the Grlcbigerince live at the bottom. Such as die 

 at the surface, and even many of those which are 

 swallowed by other animals, may retain much of 

 their protoplasmic matter when they reach the 

 depths at which the temperature sinks to 34 or 

 32 Fahrenheit, where decomposition must become 

 exceedingly slow. 



Another consideration appears to me to be in 

 favour of the view that the G-lcbigerinm and their 

 allies are essentially surface animals. This is the 

 fact brought out by the Challenger's work, that 

 they have a southern limit of distribution, which 

 can hardly depend upon anything but the tem- 

 perature of the surface water. And it is to 

 be remarked that this southern limit occurs at a 

 lower latitude in the Antarctic seas than it does 



