346 



THE GUIDE TO NATURE 



in the other places ; in a few spots in 

 New Jersey (but anything can be 

 found in New Jersey) and it is so un- 

 common that it is not mentioned in the 

 one edition of Gray's Manual of Bo- 

 tany.. A learned botanist writing on 

 the subject says : 



"The little green discs of the Duck- 

 weed [Lemna], with their slender 

 rootlets hanging beneath, reproducing 

 by branching and separation from the 

 parent disc and rarely found blossom- 

 ing, seem far enough removed from 

 our conception of a flowering plant, 

 but the still more minute U'olffia is the 

 extreme in this direction. The plants 

 consist of minute green globules about 

 a millimeter in diameter, which float 

 just below the surface of the water." It 

 is only rarely and at long intervals 

 found in bloom. 



The plant as a whole is one of the 

 most remarkable that we have ever re- 

 ceived at ArcAdiA. It has attracted 

 much attention from our visitors, manv 

 of whom have seen its details under the 

 microscope. 



Blood Corpuscles. 



BY PHILir O. GRAVELLE, SOUTH ORANGE, 

 NEW JERSEY. 



tn man the cellular elements of the 

 blood occur in two forms, the red and 

 the white (or colorless) corpuscles. The 

 red corpuscles are circular, biconcave 

 discs while the white are larger, volun- 



tarily vary in form and have well de- 

 fined nuclei. These corpuscles are shown 

 by the two accompanying photomicro- 

 graphs of human blood. Unstained 

 they are pale, but if stained by means 



BLOOD OF BIRD. 



Magnification one thousand diameters. 



of a double stain they can be readily 

 seen under the microscope. 



The proportion of white cells to red 

 is one white to about five hundred of 

 the red. The blood corpuscles of birds 

 and cold-blooded animals differ in be- 

 ing oval in shape and having elongated 

 nuclei. 



The size of the corpuscles bears no 



BLOOD OF NECTURUS. 

 Magnification one thousand diameters. 



HUMAN BLOOD. 



Magnification one thousand diameters. 



relation to the size of the animal. The 

 elephant and the humming bird have 

 corpuscles of about the same size, 

 while those of the Proteus are among 

 the largest known, those of the musk 

 deer among the smallest. 



