10 BULLETIN OF THE UNITED STATES FISH COMMISSION. 



observed in the lO-celled stage, origiuating in the manner described 

 for the Teleosteau egg by Whitman. The time of the api^earance of 

 that cavity, however, seems to vary somewhat even in different species 

 of the hitter. 



The striking simihirity of the early stages of segmentation in the 

 bhistodisk of Raia to those observed in the blastodisks of Teleosts is 

 significant, and shows that the pattern of the furrows up to the fourth 

 cleavage, in such an extremely meroblastic (teleplasmic) type of egg, 

 need uot necessarily resemble those developed on the blastodisk of the 

 equally extreme typo Aves, if Ooste's figures are correct. The figures 

 of the very early cleavage patterns of the blastodisk of the bird's egg 

 given by Coste cannot, however, be reconciled with the more recent 

 views as to the possibly intimate relation which may subsist between 

 the future axis of the embryo and the first cleavage j)lane. The detec- 

 tion of the essentially right-angled relation between the first four cleav- 

 age planes which segment the blastodisk of Bala opens uj) the question 

 whether such a method of cleavage does not also take place in the blas- 

 todisk of the bird's egg. If that is the case, then the subject of the 

 very early stages of cleavage of the Avian blastodisk needs reinvesti- 

 gation. 



A continuous series of sections was cut of the Eay's blastodisk, abover 

 described, with a Cambridge rocking microtome. In this series it was 



possible to follow out the cells and furrows shown 

 in the accompanying diagram. This series of 

 sections was prepared by cutting the disk 

 transversely. The hardening of the disk here 

 described was accomi)lished as it lay upon tlie 

 subjacent yelk undisturbed. After remaining in 

 that position for twenty-four hours in the acid, 

 the acid was gently poured off, the egg carefully 

 washed, and the disk loosened with the greatest 

 •^ ^'^' care from the underlying yelk. The changes 



Fig. 1.— Diagram of tlin . . 



ricavatro planes in tiio wrought by the acid lu tlic reuitivc positions 01 



blastodisk of Haia erina- ,, „ , ti,j, ^i 



cea. the cleavage lurrows were too slight to be noted, 



as was shown by a careful examination of the surface of the blastodisk 

 both belbre and after hardening. 



4.— FISH KIIil^KD UV POISO!VOU!>( WATER. 

 By A. II. €JI.EI¥^AW. 



[Letter to J. B. Hamilton, M. L)., Surgeou-Goueral of the Marine Hospital Service.] 



Large shoals of dead fish have been met with between Eginont Key 

 Light and Charlotte Harbor, off" the mainland, and vessels have been 

 several hours in passing through them. A few weeks ago the fishing 

 schooner City of llavaua, Capt. John Curry, lost two loads of live 



