2IO \V. M. SMALLWOOD. 



too much credit cannot be given Professor Hargitt for his per- 

 sistent experiments in trying to find a suitable fixing reagent for 

 these refractory eggs of hydroids. Had I been without the bene- 

 fit of his long experience, I doubt if the present results could have 

 been secured. He used, among fixing agents, Bouin's fluid which 

 has given the best fixation of any thus far tried and certainly 

 these preparations are superior in regard to their fixation to any 

 which he made during the preceding years of study. There is 

 very little doubt that the eggs of hydroids degenerate when left 

 in alcohol for some time and should be embedded in paraffin as 

 soon as possible. 



It seems unnecessary to review the general literature on this 

 subject for this has already been well done by Hargitt in his 

 numerous papers and by Bigelow, '08. Professor Hargitt is so 

 well known as an authority on hydroids that it has seemed 

 unnecessary for me to make an elaborate critique of his papers. 

 Therefore, I have in most instances simply referred to the pages 

 where he discussed similar phenomena, elaborating only those 

 points upon which 1 have additional data. 



ORIGIN OF THE EGGS IN Hydractinia. 



The eggs arise in the entoderm close to the basement mem- 

 brane. Certain entoderm cells are directly transformed without 

 any immediately preceding cell division. These young ova are 

 distinguished by having a large nucleus and granular cytoplasm. 

 No special region in the polyp is devoted to the production of 

 ova as Bunting, '94, maintains and text-figures I and 2 demon- 

 strate. The young ova are as likely to begin their growth in the 

 cells in the base of the polyp as in those along the side. 



GROWTH OF THE EGG IN Hydractinia. 



The first apparent change in these entoderm cells which are to 

 become ova that has thus far been observed is a marked increase 

 in the size of the nucleus before the cell as a whole has under- 

 gone any change. The result is that the nucleus occupies most 

 of the cell, the cytoplasm being liniited to a narrow border. A 

 comparison of the nuclear contents at this early stage with the 

 surrounding entoderm cells shows that the nucleolus is increas- 



