INTRODUCTION. 

 By R. M. Strong. 



During the autumn of 1913, with the aid of Mrs. Whitman, a search was 

 made in the Whitman house, and some fish-embryology records were found. 

 Among them were the descriptions of the accompanying plates. The original 

 drawings for all of the plates except Plate XXXIII were also discovered. 



Pencil marks on the original drawings assisted greatly in locating explana- 

 tory material, which was found for all of the figures in the eleven plates. It is 

 evident that these are the plates which were mentioned in the footnote (Mem. 

 M. C. Z., 1889, 14, p. 7). No other manuscript was located but the material 

 available appears clear enough. The pictures are to some extent self explanatory 

 to the embryologist who is familiar with the first paper, and a fairly complete 

 story is told by the records published in this paper. The plates pubUshed in the 

 earlier paper contained figures illustrating early cleavage stages but almost no 

 text on cleavage beyond that contained in the "explanations" of plates. Ap- 

 parently the entire history of the cleavage was planned for the later paper. 



The material found appeared in the form of descriptions of drawings (\'ery 

 likely first draft), which were fortunately grouped systematically. The records 

 were not numbered as on the published plates but bore a number which I have 

 placed in parenthesis after the number of the plate as it appears in this puljlica- 

 tion. The number in parenthesis occurred on the original drawings, in pencil, 

 in almost every case. Thus the description of Fig. 1 in Plate XXXII was 

 numbered 12 in the records left by Professor Whitman, and this number also 

 appears on the original drawing. 



It has seemed wise to do little editing, and this little has been done ^-ery con- 

 servatively. The records are consequently published largely verbatim. Signi- 

 ficant changes or additions have been placed in brackets, especially when they 

 have involved the use of considerable discretion. For many valuable sugges- 

 tions I am indebted to Prof. E. L. Mark. 



