798 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [4] 



" Eggs which had progressed a considerable way in development, so- 

 that the tail was somewhat more advanced than the stage last described^ 

 and which did not yet have the eyes pigmented, were also experimented 

 npon at this time. In consequence it was learned that such might be 

 suddenly transferred from the water in which they had previously been 

 undergoing development to the damp cotton-cloth trays without injury 

 from such sudden and continued exposure to an air temperature of 53*^ 

 r. A most striking fact was that in such as had the choroid or pig- 

 mented coat of the eyes in process of development had the formation of 

 the pigment arrested in correspondence with the general arrest of de- 

 velopment observed. 



" Returning to the eggs of the 8th June, these were examined June 

 11, 9 a. m. Development is still normal; the eyes are perfecting, but 

 the perfectly normal blastoderm does not yet quite cover the vitellus, 

 the diameter of the opening at the caudal pole, where the vitellus or 

 yelk is still exposed, being equal to about one-seventh of the circumfer- 

 ence of the egg. Temperature during tbe night 49.5° F. 



" Other lots of ova, taken on the 6tli and 7th of June, and removed from 

 the hatching-cones and put on the cloth trays in the refrigerator box, 

 have been greatly retarded, but the development is normal, no abnor- 

 malities whatever having been observed. The lot taken on the 8th and 

 I)ut into the refrigerator on the 9th, after having been in the water for 

 twenty-four hours, are well advanced, the tail being twice as long as the 

 portion of the embryo's body attached to the yelk, and the fin-folds being 

 nearly fully developed dorsally and ventrally. 



" The eggs first put into the refrigerator on the evening of the 8th 

 June now show a disposition to wrinkle, i. e., part with the water 

 inclosed between the egg-membrane and the vitellus, and are collapsing. 

 Perhaps this is due to evaporation." 



Afterwards I abandoned the view that evaporation was the cause of 

 the collapse and wrinkling of the egg-membranes. lam now fully con- 

 vinced that it was due to the invasions of a fungus. 



" Same lot of eggs of June 8 examined June 11, at 7 p. m. Blasto- 

 derm not yet quite but very nearly closed over the vitellus. Only a 

 very small round opening at the tail of the embryo marks the point 

 where its closure is about to take place. Temperature 53° F. in refrig- 

 erator. Development normal in those which are not collapsing, after 

 remaining seventy hours on the trays. 



" June 12, 11 a. m., eggs of June 8 in refrigerator for the n^ost part 

 still alive. Temperature 52'^ F, Development has been normal up to 

 this point ; the blastoderm has closed over the vitellus, and the tail is 

 just beginning to bud out as a rounded knob, as in twenty four to thirty- 

 six hour embryos hatched in water ranging from 80° to 72° F. 



" Eggs of June 7, partially developed, have commenced to collapse in 

 the refrigerator box. This appears to be due to the growth of the fungus; 

 on the ova. 



