324 SPECIAL HISTOLOGY. 



§ 222. 



Of the Blood. — The blood, so long as it is circulating in 

 the vessels, is a slightly glutinous fluid, in which only two 

 elements, the hlood-corpuscles, -globules, -cells (corpuscula s. 

 globuli s. cellulce sanguinis), the majority of which are of a red 

 colour while some are white, and the colourless blood-plasma 

 {liquor s. plasma sanguinis), are to be distinguished; when 

 excluded from the circulation, it usually coagulates entirely, by 

 the solidification of the fibrin in solution in the plasma, and 

 afterwards by the contraction of the coagulated constituent, 

 divides into the *'crassamentum" and "serum." The former 

 is of a deep red colour containing, together with the fibrin, 

 almost all the coloured, and most of the colourless blood-cor- 

 puscles, with a portion of the still dissolved parts of the 

 plasma, whilst the remainder of the latter, together with some 

 of the colourless blood- corpuscles, constitutes the serum. In 

 certain cases in Man, especially in disease, before the coagu- 

 lation of the blood has taken place, the coloured corpuscles 

 subside more or less deeply below the surface of the fluid, 



The subjoined description of the phenomena presented by the colourless corpuscle 

 (granule-cell, Jones) of the Skate will serve for all : 



" My attention was first attracted to the phenomenon, by observing a granule-cell 

 with the granules apparently escaping from it, as if burst (fig. 3). But the cell 

 soon appearing again with all the granules collected together, I was led to watch, 

 and soon perceived that the appearance of granules escaping as if from a burst cell, 

 was owing to this : The transparent and colourless cell-wall bulged out on one side, 

 leaving the granules still agglomerated and holding together, but this only for a 

 short time ; for soon, single granules were seen to separate and burst out from the 

 rest, and to enter the hitherto empty compartment produced by the bulging out of 

 the cell-wall. The regular manner in which this sometimes took place was remark- 

 able. I have actually seen the granules enter the compartment by one side, and 

 circulate along the bulging cell-wall to the other side, until the whole compartment 

 became filled with granules. This having occurred, the bulging began to subside, but 

 was succeeded by the bulging of another part of the cell-wall, into which again a flow 

 of granules took place, and so on all round the cell." 



We have already pointed out the occurrence of similar amceba-like movements in 

 the young cells of mucous membranes detached during slight inflammation, and in 

 the cells of the gelatinous tissue of Medusse ; and we think that, very probably, it 

 will eventually be found to be a property of all young periplastic substance. 



MM. Guerin-Meneville (1849-51), Davaine (1850), and Robin (1853), appear also 

 to have observed these amaba-\ike movements, without being acquainted with 

 Mr. W. Jones's essay. (See the ■ Histoire nat. des Vegetaux parasites,' by M. 

 Robin, p. 567.)— Eds.] 



