of the Fishery Board for Scotland. 



221 



the direction of their 1 drift/ for, with a sufficient number of experi- 

 ments, one can follow the course of a certain mass of eggs, capturing 

 them at different stages at different stations, but this would scarcely be 

 worth the trouble in its execution ; for the determination of the rate of 

 drift is not of prime importance, and may be inferred upon a knowledge of 

 the other factors. 



There are now to hand a very complete series of temperature-observa- 

 tions taken in the different areas around our coasts, and these should be 

 available for determining the time taken by the egg to develop. 



An amplification of Dannevig's experiments would furnish us with the 

 time of development of our common eggs under varying degrees of tem- 

 perature, so that by experimental evidence we may be able to pronounce 

 exactly how long an egg of a given species will take to develop when 

 spawned in a certain area; in other words, we have the time of the ' pelagic 

 period ' as determined by developmental processes, as controlled by the 

 temperature, and, as we have by the drift-bottles a possible means of 

 determining the direction of drift, eventually inshore, we can, if desired, 

 deduce the rate. 



For all practical purposes we need only require to determine (1) the 

 direction of drift after spawning ; (2) the time taken in development. 

 Although, in special cases, these might be determined by a study of 

 pelagic eggs, and their distribution and their bearing on the consideration 

 of the two preceding sections must be borne in mind, yet they are both 

 more readily made out by the experimental processes as instanced above. 



TABLE I. — EGGS OF COD. 

 The Cod (Gadus morrhua). 

 Firth of Forth. 



Feb. 19, 1891. Station VIII., 



„ 19, „ ,, IX., . 



,, 21, 1893. E. of May Island, . 



Mar. 16, 1892. Station VIII., 



„ 16, „ „ IX., . . 



„ 19, 1891. ,, V., . 



,, 19, 1895. „ VII., 



„ 19, „ „ VIII. and IX., 



„ 29, 1894. „ V., . 



,, 30, 1891. ,, II., . 



April 3, 1893. E. of May Island, . 



,, 4, ,, 10 miles S. of May Island 



,, 4, ,, 9 miles S. of May Island, 



,, 5, 1895. Prestonpans to mid-Forth 



,, 5,1892. E. of May Island, . 



6, ,, Cross-section I., 



„ 8, 1891. South Bay, . 



„ 8, 1892. Fidra to Elie Ness, 



,, 9, ,, Inchkeith, . 



„ 10, 1891. E. of Portobello, . 



,, 11, 1892. Cross-section III., 



,, 13, 1891. Liston Bank, 



„ 14, ,, Station VIII., 



„ 16, 1892. ,, V., . 



„ 16, 1894. ,, I., . 



„ 16, „ „ III., . 



„ 17, „ „ VIII. and IX., 



„ 17, „ „ V., . . 



„ 18, „ „ VI., . . 



,, 19, 1893. ,, II., . 



„ 19, „ „ III., . . 



,, 19, 1892. Cross-section III., . 



,, 20, 1893. Station I., 



„ 21, 1892. „ II., . 



Ova of cod. 



Numerous. 



2. 



45. 



50. 



Ova of cod. 



Ova of cod. 



40 (very advanced). 



90 (cod and whiting). 



85. • 



170. 



500 (cod and whiting). 

 Some cod ova. 

 Ova of cod. 



Considerable number of cod. 

 91. 



A few ova. 

 87. 



Vast number. 



> 3 ft 



Many (all well-developed). 



12. 



4. 



940. 

 101. 

 13. 



Eggs in abundance. 

 Ova of cod. 



Ova of cod (nearly hatching). 

 36. 



Few (advanced). 



