THE BLOOD, LYMPH, AND HISTOLOGY 0¥ THE VESSELS. 263 



b. The corpuscles are of two kinds, colourless and coloured. 



(i) The colourless or white cor^iuscles are subspherical masses o£ 

 jjrotoplasm, endowed with the power of spontaneous motion. They 

 are much fewer than the red cor2)uscles, thoug-h the proportion of 

 white to red varies consideraLly. Three chief varieties of colourless 

 corpuscles can be distinguished, all of which are true cell forms, 

 and behave like other cells with staining- or other reag'ents. They 

 have no cell- wall, but are simply nucleated masses of protoplasm. 

 These corpuscles possess the power of passing through the walls 

 of the blood-vessels, and are then known as mig-ratory cells ; such 

 migratory cells can be found in nearly all tissues, but more espe- 

 cially in the connective-tissues. 



a. Ordinary large colourless corpuscles are large transparent 

 masses of protoplasm containing one or two nuclei, rarely three 

 or more. The cell contains few granules, and usually has one or 

 more vacuoles or clear sj^aces containing fluid. 



j3. Granular corpuscles are less numerous than the foregoing-, but 

 larg-er, and are distinguished by the numerous large dark granules 

 which they contain. The processes such a corpuscle sends out are 

 hyaline. 



y. Smaller corpuscles also occur varying much in form: they may 

 consist of a nucleus \\ith a very small amount of hyaline or granu- 

 lar protoplasm, or of se\'eral nuclei with an extremely small amount 

 of protoplasm. 



(2) The coloured corpuscles are much more numerous than the 

 colourless corpuscles ; each is a bi-concave, oval disc, about 

 0-0255 ^^^1^^- i^^ length, and 0-017 ^^™- i^^ breadth (Gulliver)^ 

 (R. temporaria, 0-0235 and 0-0145 mm. respectively). Each cor- 

 puscle possesses an oval nucleus (Hewson) ^, which projects into 

 either concave surface of the whole corpuscle. These corpuscles 

 do not possess the power of spontaneous movement; and have no 

 cell-wall. The corpuscles are of a reddish -yelloAv colour, and 

 give the blood its characteristic hue. The colouring- matter is 

 haemoglobin, and when separated it crystallizes in prisms (Preyer). 

 The corpuscles show a well-marked intracellular and intranuclear 

 network.] 



^ Gulliver, Proc. Zool. Soc. London, 1845, Vol. XIII, p. 93 seq. 

 - Hewson, Phil. Trans. 1773, VoL LXIII, p. 310 seq. 



