Royal Society. 449 



constantly observed in the blood of vertebrata; and lastly, i\ie discs, 

 wliich are further developments of the spherules, and analogous to 

 the true red blood-discs of the higher animals, and which, as he 

 states in a subsequent part of his paper, in his examination of the 

 blood of the human foetus, he believes that he has also traced from 

 the white, opake granules or spherules. 



The author then proceeds to describe these forms of the corpuscle 

 in insects more minutely, and enters into considerable detail with 

 reference to the oat-shaped corpuscle, tracing it from its earliest 

 distinct form, before any nucleus is perceptible in it ; and shows that 

 the nucleoli which constitute this body are gradually increased in 

 number, until the corpuscle has attained its full size, when it first 

 changes its form and becomes shorter, then rounded, and afterwards 

 entirely breaks up and liberates the nucleoli that have been deve- 

 loped within it. This change of form he shows always takes place 

 very rapidly in all the oat-shaped corpuscles, large and small, when 

 out of the body, and to this circumstance he attributes the diversity 

 in the descriptions that have been given by various observers of the 

 form of the corpuscle. He shows also, that, with reference to the 

 function of this body, the corpuscles are usually found in greatest 

 number during the act of breaking up, immediately before the larva 

 is preparing to change its skin, at which time the blood is extremely 

 coagulable ; and that there are fewest corpuscles, or that there is the 

 greatest number of small corpuscles of this kind, soon after the cater- 

 pillar has again begun to feed. When the insect has assumed the 

 pupa state, nearly the whole of these corpuscles are broken up. The 

 greatest abundance of them is found in the act of changing on the 

 third or fourth day of the pupa, after which the number of these 

 corpuscles is gradually lessened, until, when the insect has entered 

 the perfect state, very few remain. When the change to the perfect 

 insect occurs, there is another opportunity of watching the function 

 of this corpuscle. When the wings are being expanded and still 

 soft, a few oat-shaped corpuscles circulate through them ; but as the 

 wings become consolidated, these corpuscles appear to be arrested, 

 and break down in the circulatory passages, supplying directly the 

 material for the consolidation of these structures ; as appears from 

 the entire arrest of circulation in these parts, and from the granular 

 remains of the corpuscles which may be seen by transmitted light in 

 a wing completely denuded of its scales on the upper and under sur- 

 faces. The spherules and discs of the perfect lepidopterous insect 

 are then noticed ; and some peculiar clavate or fiddle-shaped bodies, 

 which appear to be the transition forms between spherules and discs, 

 are pointed out as occurring in the blood of one of the night moths, 

 Xylophasia polyodo7i, and also in the butterfly soon after it has left 

 the pupa state. These facts are regarded as proofs, derived from 

 direct observation, of the function of the corpuscle, and of its ana- 

 logy, both in function and development, to the secreting cells of 

 glands. 



In the second division of his paper, the author draws some com- 

 parisons between the blood-corpuscles of insects and the vertebrata, 



Phil. Mag. S. 3. Vol. 26. No. 174<. May 1845. 2 H 



