114 MANUAL OF HISTOLOGY. 



others, which has been set down to a certain clamminess of their surface. 

 Again, they are specifically lighter than their red companions. In a 

 drop of blood copiously diluted with water they gradually collect on the 

 surface. We will refer again, lower down, to their position in whipped 

 as well as coagulated blood, as the best proof of their lower specific 

 gravity. 



REMARKS. 1. It is now many years since Wharton Jones first demonstrated finely 

 and coarsely granular lymph-corpuscles in the blood of the most different vertebrates. 

 (Philosoph. Transact. 1846, Part II. p. 63. ) 2. Whilst the red blood-cell of the human 

 being is incapable, owing to its characteristic peculiarities, of being confounded in 

 any way with other cells of the body, it is quite another matter with the colourless 

 corpuscles. In many fluids of the system, containing protein matters in solution, 

 we meet with very similar, or more correctly, identical cells ; in chyle, in lymph, 

 mucus, pus, and saliva; to distinguish these from the others is impossible. There 

 can be hardly any doubt, also, that the deviations from the typical form mentioned 

 above, may be partly owing to differences in age ; but to determine which are old 

 cells and which young is hardly possible. These colourless elements exist also in the 

 blood of animals, but subject to less variation as to size than the coloured. Accord- 

 ing to the dimensions of the latter, they may be the largest or smallest of the two 

 species. 



70. 



In fresh blood the red cells give no signs of an active change of form, 

 and are only remarkable for their elasticity and extensibility. The white 



corpuscles, on the other hand, belong, 

 in almost every case, to the class of con- 

 tractile cells already mentioned ( 49) ; 

 and can retain this power of motion for 

 many days in blood which is preserved 

 cool. In cooled preparations, however, 

 these changes of figure can only be re- 

 cognised with difficulty, and take place 

 but slowly (fig. 117). But the whole 

 scene is changed if the normal tempera- 

 ture of the body be artificially main- 

 tained during examination (fig. 118). 

 We can then distinguish a lively de- 

 velopment of frequently very long pro- 

 cesses, and wonderful configurations of the lymph-corpuscle. The latter 

 creeps at the sa"me time hither and thither over the glass plate, and takes 

 up small particles of any matter in the neighbour- 

 hood into its interior, such as cinnabar, carmine, 

 or milk-globules, &c. But for this it is requisite 

 that the lymph-corpuscle have attained a certain 

 magnitude ; smaller ones put forth but inconsider- 

 able processes, and do not alter their position, while 

 the most minute, measuring perhaps G'0050 mm., 

 do not even possess the power of varying their 

 shape. 



These changes of form and locality of the lymph- 

 corpuscle may be also very easily seen in the blood 

 of cold-blooded animals : the frog and salamander 

 them contain particles of afford excellent examples. 



The number of white blood-cells compared with 



the coloured is always inconsiderable, and in the human being as a rule 

 very small; to a thousand of the latter we find at most two or three 



