136 



THE ORIGIN OF YOLK IN THE OVA OF AN 

 ENDOPARASITIC COPEPOD. 



By H. Leighton Kesteven, D.Sc, M.B., Ch.M. 



(Plate iii.). 



In January, 1905, Professor J. P. Hill presented me with 

 material for the study of the morphology and development of an 

 endoparasitic copepod infesting Ftychodera an.sfralu'usis Hill. 

 The parasite was found to be new, and was subsequently described 

 under the name of Ubius hilli Kestv., in 1913(3). The following 

 observations were made on the developing, ultimate oogonium, 

 and primary oocyte at the time U. hilli was studied (1908), and 

 were submitted to Prof. Hill for criticism. At his suggestion, 

 this paper was withheld from publication because, at that time, 

 the material on which the observations were made was all stained 

 in one way. Since then, I have obtained fresh material, which 

 was fixed in {a) 5% formaldehyde in seawater; and (h) Miiller's 

 bichromate-solution. Specimens, after cutting, were stained with 

 (1) Delafield's htematoxylin, (2) in Heidenhain's haematoxylin, 

 (3) Mayer's carm-alum, (4) Flemming's method for karyokinetic 

 figures. 



This staining was done over three years ago, but press of 

 other work has, till now, prevenced me from examining the 

 results. Recently, I have found time to go over these sections, 

 and I find that I have nothing to add to the original paper. I 

 am satisfied, that the observations recorded truly represent pro- 

 cesses taking place in the developing cell, and are not artifacts, for 

 I find the cells to present these appearances, not only in different 

 specimens similarly stained, but also in the same and in different 

 specimens dissimilarly stained. Were I situated in a city near 

 a library, I doubt not I would hnd many reasons for altering 



