RIVER FISHERIES. 97 



It is scarcely necessary to add that the microscope shows other and 

 smaller ovarian eggs. An ovary of the size above mentioned con- 

 tains about 70,000 ova, ready to be laid. Their diameter increases, 

 as soon as they are put in water and impregnated, from 9-100ths to 

 13-100ths of an inch. This is by the endosmosis of water between 

 the yoke and the shell membrane.* Of the embryonic development, 

 we have, as yet, only an imperfect outline to present. Forty-one 

 hours after impregnation, the condition of the embryo is, on the 

 whole, in advance of that of coregonus on the thirty-third day. The 

 under surface, from the nose to the beginning of the ventral, is in 

 close contact with the yolk, which is composed of a great number of 

 rounded divisions, such as are seen in the complete segmentation of 

 that body, while its surface is flecked with pigment stars, of which a 

 less number may be distinguished on the forward part of the trunk. 



LEGISLATION, 1868. 

 AS TO FREE PASSAGE OF FISH, BY FISHWAYS, OVER WEIRS, 



By the law of this Commonwealth, all persons who may build dams 

 on streams annually frequented by fish, do so under an obligation to 

 keep open sufficient fish-ways for the passage of such fish ; unless 

 they are relieved by a special Act of the legislature. 



The following is the legislation which concerns this Report more 

 particularly : 



[CHAP. 62.] 



An Act to protect the Shad Fishery in the Connecticut River. 

 Be it enacted, fyc., as follows : 



SECT. I. No person shall set, draw, or sweep any seine or net, 

 the meshes of which are less than two and one- fourth inches square 

 when new and dry, for the purpose of catching shad or any other fish 

 in that part of the Connecticut river which is within the limits of 

 this Commonwealth, and below the dam across said river at Holyoke, 

 between the first day of May and the fifteenth day of July, during 

 each year. 



* The same takes place in a less degree in the egg of Coregonus (white fish.) 

 (Carl Vogt, loc cit. p. 27, PI. I fig. 9.; Accustomed only to eggs of trout, Green 

 was much astonished to behold the mass of ova swell to near twice its first bulk. 



