234 RED PARTICLES 



cular, like those of the common fish (cxvn), and have each of 

 them a lesser particle in their centre, as those of other animals. 

 But there is a curious change produced in their shape by being 

 exposed to the air, for soon after they are received on the glass 

 they are corrugated, or from a flat shape are changed into 

 irregular spheres, as is represented in Plate V, fig. 12. This 

 change takes place so rapidly, that it requires great expedition 

 to apply them to the microscope soon enough to observe it. 



I have observed the sanies or blood of a shrimp, by cutting 

 off its tail, and found vesicles in it similar to those of the lobster, 

 which have been a short time exposed to the air. But I never 

 could apply the blood so as to see them in their flat form ; 

 but since they change by exposition to the air, I conjecture that 

 like the lobster's they are flat in the blood-vessels, but being 

 more susceptible of changes from the contact of air, they were 

 corrugated before I could get them applied to the microscope. 



The ingenious Leeuwenhoek has observed, that in the blood 

 of a grasshopper, its vesicles or globules, as he calls them, are 

 green ; I have seen the same circumstance in the white cater- 

 pillar, whose serum appeared green when in its vessels, but 

 when let out from this animal, or from a grasshopper, the 

 colour cannot be distinguished. 



The smallest animal in which I have discerned these vesicles 

 is an insect no bigger than a pin's head, that is seen almost 

 constantly in the river water which we have in London. This 

 insect, which is a species of the monoculus, being put into a 



(cxvu.) On the blood-corpuscles of fishes, see the observations of 

 Professor Wagner. a The majority of the corpuscles in osseous fishes 

 are of a rounded oval ; in some species, considering the breadth of the 

 corpuscle as 1, the length would be from 1| to If: the nuclei are, 

 commonly, nearly round, and the envelopes very delicate and evanescent, 

 as stated in Note cm. Sometimes, as in the pike, the corpuscles are 

 rather angular or pointed at the ends. In the cyclostomes the corpuscles 

 are of the same figure as those of man, and only slightly larger ; while 

 in the sharks and skates the corpuscles are much larger, oval, and re- 

 sembling those of the frog. In Mr. Yarrell's lancelet (amphioxus), 

 mentioned in Note CXXXTII, the blood is said to be colourless, and its 

 corpuscles like those of lymph. 



The corpuscles of mammals, birds, and reptiles, are described in 

 Note XCVITI, and measurements of the whole are given in the Tables 

 at the end of this chapter, Note cxvm*, pp. 237 et seq. 



a Physiology, tr. by Dr. Willis, i, 238. 



