484« The Rev. M. O'Brien's Reply to some Observations of 



1 3. Yellow Bunting [Emheri- 

 za Citrinella, Linn.). 

 1-5333 



12. House Sparrow {Frin- 



gilla domestica, Linn.). 



1-6000 



1-4570 



1-6400 

 1-3200 



1-4682 



1-4572 



1-6400 

 1-3200 

 1-4572 



These measurements, excepting No. 5, were obtained from 

 the particles of adult birds at different seasons. The lymph- 

 globules in most of the above-named species, do not differ 

 much in magnitude ; and it is possible that further observa- 

 tions may show as much variety in the size of the globules of 

 any one bird, especially if examined at different periods and 

 compared in growing and mature specimens. In a few instances 

 from one to five of the globules were seen to be inclosed with 

 granular matter in a cell, the diameter of the latter varying 

 from l-2600th to 1-1 114th of an inch. If the lymph-globule 

 be regarded as a cell-nucleus, of course the smaller rounded 

 particles which it frequently contains will be nucleoli. Some- 

 times from two to six of these may be observed in one lymph- 

 globule, in which case they are very minute ; and it is not 

 unusual to see a single central and larger nucleolus varying 

 from a quarter to half the size of the lymph-globule. 



LXXII. A Reply to some Observations o/Trofessor Kelland 

 in the Philosophical Magazine for May 1842. By the Rev. 

 M. O'Brien, late Fellow of Cains College, Cambridge''^-. 



THE observations made by Professor Kelland upon my 

 paper published in the Philosophical Magazine last 

 March, are calculated, I think, to produce an impression, 

 that I have done nothing more than he has already done in 

 his memoirs in vol. vi. of the Camb. Phil. Trans., and his 

 ' Theory of Heat.' This imposes upon me the disagreeable 

 task of defending myself in the following manner. 



I shall briefly state how far I have pursued the same course 

 as Professor Kelland, and in what we differ. 



I have made use of a notation similar to that employed by 

 Prof. Kelland ; I have assumed that the particles of aether 

 are acted upon by those of matter ; and I have employed the 

 equations of M. Cauchy, viz. 



* Communicated by the Author. 



