The use of the ultra-microscope and ciark ground 

 illumination, have of late made things so much easier for 

 us in this respect. 



I have with me this evening some very old books, 

 whose illustrations give proof of the most painstaking and 

 accurate observation. One book, dated 1741, was written 

 by Wm. Cheselden, one of the foremost surgeons of the 

 day in England. He lived 1688-175 2, and this book is 

 the sixth edition of his famous text-book. In it are figured' 

 arteries and veins, living sperm cells, and an admirable 

 drawing of "the circulation of the blood in the fish's 

 tail, as it appeared in a microscope." 



The Liverf>ool Medical Institution has very kindly 

 permitted me to show you Leeuwenhoek's works in four 

 volumes. Leeuwenhoek, with his simple microscopes, 

 taught us the value of minute observation, and upon his 

 discoveries, Malpighi (1653) in England completed the 

 proof of Harvey's circulation of the blood, showing 

 how it flowed from the arteries to the veins. We hardly 

 realize in these days the importance of this observation. 

 Up till then the veins were known to be filled with blood, 

 but the arteries were supposed to be filled with air,simply 

 because they were empty after death. To-day the 

 surgeon operates in comparative safety, and hardly a drop 

 of blood is lost, but in those days post-operative 

 haemorrhage was a doctor's terror, and now all this is a 

 thing of the past, just because we tie a ligature and stop 

 the flow, which was so beautifully shown in the newt's 

 tail, the frog's lung, or the bat's wing. 



Another old book which will interest you is a volume 

 of an Encyclopaedia, dated 1797, in which are two 

 admirable articles, one on medicine, the other on the 

 microscope. The latter article shows illustrations of 

 nearly all the microscopes, both single and compound, as: 

 used at that time in England. 



