INTRODUCTION OF THE MICROSCOPE 63, 
It is very interesting to note that in connection with this 
work he actually observed the passage of blood through the 
capillaries of the transparent lungs of the frog, and also in 
the mesentery. Although this antedates the similar obser- 
vations of Leeuwenhoek (1669), nevertheless the work of 
Leeuwenhoek was much more complete, and he is usually 
recognized in physiology as the discoverer of the capillary 
connection between arteries and veins. At this same period 
Malpighi also observed the blood corpuscles. 
Soon after he demonstrated the mucous layer, or pigment- 
ary layer of the skin, intermediate between the true and the 
scarf skin. He had separated this layer by boiling and 
maceration, and described it as a reticulated membrane. 
Even its existence was for a long time controverted, but it 
remains in modern anatomy under the title of the Malpighian 
layer. 
His observation of glands was extensive, and while it must 
be confessed that many of his conclusions in reference to 
glandular structure were erroneous, he left his name connected 
with the Malpighian corpuscles of the kidney and of the 
spleen. He was also the first to indicate the nature of the 
papilla on the tongue. The foregoing is a respectable list of 
discoveries, but much more stands to his credit. Those which 
follow have a bearing on comparative anatomy, zodlogy, and 
botany. 
Monograph on the Structure and Metamorphosis of the 
Silkworm.—Malpighi’s work on the structure of the silkworm 
takes rank among the most famous monographs on the 
anatomy of a single animal. Much skill was required to 
give to the world this picture of minute structure. ‘The mar- 
yvels of organic architecture were being made known in the 
human body and the higher animals, but “no insect—hardly, 
indeed, any animal—had then been carefully described, and 
all the methods of the work had to be discovered.” He 
