758 



DEPTHS OF THE OCEAN 



least, and as only very few individuals grow to a large size, this 

 group must be considered as 'full-grown' blennles. In other 

 words, it takes the blennies 2^ to 3 years to become 'full-grown.'" 

 This account contains the foundation of this branch of 

 science and a programme for further investigations, which 

 have been employed in many recent researches, and will in 



future be employed 

 along with more 

 modern methods. 



Another important 

 series of investigations 

 was inaugurated by 

 Heincke, who endea- 

 voured to employ the 

 methods of anthro- 

 pology by recording 

 various dimensions of 

 the organisms in order 

 to characterise varia- 

 tions in growth pecu- 

 liar to a species in 

 different areas of the 

 sea. Heincke mea- 

 sured the length and 

 height of body, length 

 of head, etc., in a great 

 number of herrings 

 from various marine 

 areas, and he found the 

 relations between these 

 dimensions to be so 

 characteristic that he 

 supposed the herring to be subdivided into various races, each 

 constituting a peculiar type of growth. 



These two methods are, however, useful only as long as one 

 can operate with great numbers of measurements according to 

 the principles of the statistical method, and it proved in many 

 cases impossible to determine the age and the type of growth 

 of each individual by these methods. As regards the study of 

 age alone this proved a great obstacle, especially in regard to 

 the older animals. It was therefore very important to find a 

 method which would give the age of each individual and define 

 Its particular type of growth. 



H. Heincke. 



