54.6 



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 liglit in 

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

 faces. The sphemles 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 polyodon, 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, 

 and gives the details of a series of observations on the blood of a 

 human foetus that was born alive at the end of the sixth month. 

 He examined the blood of the parent, and of the placenta, and also 

 of different parts of the body of the foetus a few hours after death, 

 and found in general that the blood of the parent contained a very 

 large quantity of white chyle corpuscles, and was extremely coagu- 

 lable : the blood of the placenta contained, beside an abundance of 

 chyle corpuscles, red blood-discs of extremely variable sizes, the 

 largest being one-third or one-fourth larger than those of the 

 mother, and the smallest scarcely more than one-fourth as large as 

 the largest. There were also an immense abundance of molecules 

 and nucleoli, from which latter the red blood-discs appeared to be 

 developed. The blood of the vein and lungs presented a similar ir- 

 regular condition as to size of the corpuscles, while that of the left 

 auricle of the heart, aorta and arteries of the cord was more uniform 

 in its character. From these observations the author concludes, 

 that the blood of the vertebrata is analogous in its mode of develop- 

 ment to that of the insects and other invertebrata, and that the red 

 blood-discs are the jiltimate developments of the opake white gra- 

 miles or nucleoli of the blood. 



Drawings illustrating the subjects accompany the paper. 



