500 LIFE IN THE OCEAN. 



succeed in gaining a tolerablj'^ exact idea of the distribution of eggs, 

 and consequently in acquiring practically important knowledge con- 

 cerning the situation and extent of the places preferred by the fish 

 for la^dng their spawn. These experiments will also furnish valuable 

 data in regard to the quantities of eggs laid by each kind of fish. It is 

 even possible to pursue quantitative experiments, showing the loss at 

 each period of the development of the larvae. Knowing the quantity 

 of eggs which each species of fish can give, we can finally deduce from 

 the figures furnished b}^ these soundings the quantity of fish really 

 existing in the waters under study at the spawning season. The com- 

 parison of the figure so obtained with the statistics of the fisheries will 

 give the ratio between the fish taken and the annual increase. 



This method is the only one hitherto proposed which permits us to 

 get an exact idea of the situation. It has thus far only been applied 

 to the fisheries of the Kieler Bucht (la rade de Kiel) in the Baltic and 

 of the German Ocean. These applications have shown that the method 

 is correct in principle and reliable in its application. New observa- 

 tions, however, on fish eggs and their development are yet needed to 

 give the process an absolutely certain basis. These observations are, 

 moreover, indispensa))le in order to elucidate a number of important, 

 practical, and scientific questions. A quantity of isolated experiments, 

 hitherto of no particular consequence in default of any general prin- 

 ciples ])y which they might be interpreted, become to-day indispensable 

 bases of further researches. 



The animals which inhabit the sea are developed in proportion to 

 the ({uantity of their food. Now, since all this food comes directly or 

 indirectly from plants, it follows that we can just as well estimate the 

 real production of animal life in the water by means of the annual 

 yield of vegetation as we can estimate the product of a farm by the 

 quantity of grass and fodder that it affords. The vegetable produce 

 of the sea belongs to two forms marlcedly distinct. On the one hand 

 there are the multicellular shore plants of some size, such as fucus or 

 wrack, sea lettuce and green seaweed generall}^ (algues vertes), dulse 

 and other florid seaweed (algues rouges), and kelp (herbe marine). On 

 the other hand there are unicellular organisms so small that with a 

 very few exceptions, the}' are not distinguishable by the naked eye. 

 The large plants are all collected into a narrow band along the shore, 

 while the njicroscopic plants are not only found on the ])order and 

 at the bottom of shallow arms of the sea, but constitute an essential 

 part of the plankton which floats freely in the water. Ideas of the 

 relative importance of the two classes as food are widely divergent 

 owing to the insufliciency of observations hitherto made upon the sub- 

 ject. But if we consider the ocean as a whole, it can hardly be doubted 

 that the quantity and consequently the direct importance of fucoids, 

 florids, and algae generally is very feeble as contrasted with that of 



