the Animals of the Deep Seas. 203 



Of all the movements which convey organic materials to the 

 sea-bottom, descending cuiTents are evidently among the most 

 eflScacious. Their operation falls precisely in the most suitable 

 season for this purpose : it commences after the annual deve- 

 lopment of the marine vegetation in the temperate and cold 

 zones has attained its maximum, when strong and long-con- 

 tinued storms gather their chief harvest in the fields of Zos- 

 tera and tangle, and the bottom of the sea is disquieted to a 

 greater depth than usual. 



I am well aware that between a small bay like the harbour 

 of Kiel and an ocean such as the Atlantic there is a great 

 difference of space. But, as we know, by persistent operations 

 Nature can bring the same things to pass in great spaces 

 which are completed by her in smaller ones in less time. The 

 slowness with which plants decay under water is very favour- 

 able to their long transportation before complete decomposi- 

 tion. 



Wherever animals were found in great depths, the bottom 

 was muddy. It is worth inquiry whether on elevations (on 

 which little or no mud can remain lying, because the bottom- 

 currents, being contracted there, must sweep the bottom more 

 strongly) the population is not also feebler than in the deep 

 valleys which abound in mud. In the bay of Heligoland 

 those parts of the sea-bottom where the strong current allows 

 neither living plants to grow nor dead ones to rest are very 

 poor in animals. 



According to all that we know about the distribution of 

 animals on land and in the shallower parts of the sea, we 

 must assume that the distribution of the deep-sea animals also 

 is chiefly dependent on the presence of vegetable substances. 

 And as yet we have only become acquainted with deep-sea 

 animals which belong to classes living also in higher regions, 

 and which consequently will partake of the same essential 

 conditions of life with these. 



To suppose that the simplest organisms originate at the 

 bottom of the sea by primitive generation {generatio primaria) 

 has something very seductive about it. It suits wonderfully 

 well with old cosmogonies and new theories. But we shall 

 never succeed in demonstrating its occurrence there. And 

 even if we could methodically produce primitive generation in 

 our laboratories, we could assert nothing further than that 

 perhaps such primitive generation may take place also at the 

 bottom of the sea. 



