36 



sulphate of lime, carbonate of lime and silica, for organic 

 matter in fossils), tlie skeleton of the former -wood has been left 

 with a body strangely transformed into a mineral, that might be 

 suspected in animal but least in vegetable remains. 



August 2ncl, 1877. 



Structure of the Red Blood-corpuscles. — Mr. Hammond read a 

 paper, illustrated by several drawings, on the interesting and 

 vexed questien concerning the existence of a nucleus in the living 

 red blood-corpuscle of viviparous vertebrates. lu his paper, read 

 at a late meeting of the Society and published, witli engravings 

 in the " Montlily Microscopical Journal" of last June, he an- 

 swered the question in the affirmative as regards fish, demon- 

 strating plainly the presence of the nucleiis in the living red 

 corpuscle as it flows in the minute veins of the yelk -bag of the 

 young trout ; and he now extends his observations, with the 

 same result, to several mature fish of different species. Further, 

 he submits to examination the corpiiscles while they are alive, 

 andflowing within the blood-vessels of frog-tadpoles and in a bird. 

 The latter was the J'ouug duck, just hatched, in whic'h Mr. Ham- 

 mond found the edge of the foot-web sufficiently thin and trans- 

 parent to allow of the circulation being well seen under a deep 

 magnifying power. The residt was still the same as in the fish, 

 the nucleus being plainty seen in most of the red corpuscles 

 while they were flowing in their containing veins or capillaries. 

 In the frog, owing to the larger size and substance of the cor- 

 piiscles, the nucleus was not so easily seen ; but after careful 

 adjustments of the focus the nucleus was demonstrable. Hence, 

 in three classes of the oviparous vertebrates, he concludes that 

 he has demonstrated the presence of a nucleus in the living red 

 blood -corpuscle ; and he supposes that one reason why Professor 

 Savory and others coidd not see it, was because the corpuscles 

 swell or become circular during stagnations ; and contracting 

 again and becoming transparent, when they escape from their 

 vessels or to the object-plate, allow tlie nucleus to be seen, as all 

 observers agree that it is then plainly visible. The point em- 

 braced by Mr. Hammond's researches is important, because, in- 

 dependently of the mere physiological cpiestion, it has a wide 

 taxonomic significance, shoT;\'ing the validity of Professor Gulli- 

 ver's two great divisions of vertebrates into Pj-renaemata and 

 ApjTenaemata. Mr. Hammond's drawings well exhibited the 

 softness of the coi-puscles and how they either tail- out or other- 

 wise alter in shape when passing a narrow channel ; and in one 

 of his sketches from the tadpole there -was an admirable view 

 of the nucleus in the fore-part of the corpuscle, and the envelope 



