Part III. — Si):tee7Uh Annual Report 



Water Percentage of Demersal Ova (Immature and Mature). 





Immature. 



Mature. 



Herring, 

 Cottus Scorpius, 

 Cat-fish, 

 Lumpsucker, 

 Lopbius, 

 Salmon, 

 Trout, 

 Conger eel. 



Sturgeon, 



46-07 



32-00 

 7*10 (very immature) 



9-41 (with some ovarian 

 tissue) 



36-93 



70- 72 and 69-36 

 74-46 



71- 30 

 70-46 

 68-7 

 56 7 

 60-9 

 57-7 



Here it is at once noted that the percentage of water in each mature 

 pelagic ovum is much higher than in the demersal ones. 



It is of more importance to compare the fully mature ova of each class 

 rather tlian the immature, as the latter m;iy be obtained at all stages of 

 maturation. 



What occurs in all cases is a gradual passage in of water during the 

 process of maturation. In the pelagic the process goes further than in 

 the demersal ovum. 



The mature eggs with the highest percentage of water are undoubtedly 

 those of the whiting and haddock. The percentage of water in the fully 

 ripe ova is very constant. I have examined large numbers of plaice, 

 haddock, cod, and whiting ova, and in all cases have found the percentage 

 of water to remain almost at the same figure. One has, of course, to be 

 careful that in removing the ovarian fluid one does not break the 

 ova, as the viteUin fluid then escapes, and during the weighing 

 evaporates off* 



I have not inserted my analysis of the unripe saithe and flounder, as 

 the results obtained were vitiated by the fact that I could not obtain the 

 eggs unbroken and yet freed from ovarian fluid. 



Weight of the Fresh Ova of Different Species of Marine 

 Teleosteans in the Immature and Mature Conditions. 



As previously mentioned, if one could calculate exactly the volume of 

 the ova from their diameter, it would be an easy matter, knowing their 

 weight, to state their specific gravity; but, unfortunately, the volume 

 cannot be correctly determined from the diameter as the eggs are not 

 absolutely spherical. 



If we, however, can determine the weight of the ova, and also find out 

 the amount of water, salts, and organic constituents present at different 

 stages, one can determine whether the increase in volume be due simply 

 to a passage in cf water, or of a watery solution containing salts, or of a 

 weak all}umi]ious solution. 



In the following Tables I shall give the weight of different immature 

 and mature ova. I shall first take up the pelagic and then the demersal 

 ones : — 



