The Dawn of Microscopical Discovery. By C. Singer. 337 



and even figured. He suggested that some of these were the cause 

 of plague, a doctrine which became popular at the time, and was 

 developed by Athanasius Kircher. 



5. He made a special study of certain small spiders, examining 

 and carefully enumerating the number and distribution of their 

 eyes, which were shown to Vary in different species. The crystal- 

 line structure of the eyes was distinguished. In some spiders, as 

 well as in lice, Borel thought he could see the contractile motion 

 of the heart. 



6. Ants were examined and found to be possessed of eyes 

 derived from those in the larva 3 , and the larval nature of the so- 

 called ant's-eggs was demonstrated. The eyes of flies were found 

 to have many facets, the number being estimated at 300. He 

 clearly saw the terminal claws of the fly's leg, and likened them 

 to those of a lion. 



7. Silkworms were shown to secrete their silk not from the 

 mouth, as had been previously supposed, but from little teat-like 

 processes, the thread subsequently passing through and being 

 guided by the jaws. 



8. Some of Borel's most remarkable observations were made on 

 plant anatomy, and have been unaccountably passed over. He 

 saw minute markings on young leaves which were probably out- 

 lines of cells, and he has one passage that apparently describes the 

 movement of protoplasm, an observation which preceded that of 

 Corti on Chara by more than 100 years. He appears to have seen 

 the stomata on leaves, and to have fully realized their power of 

 opening and closing. He followed up Cesi's observations on the 

 fronds of fern and saw the spores. 



9. The first microscopical observation of medical value was 

 made by Borel. He succeeded in making out ingrowing eyelashes 

 which were invisible to the naked eve, and whose removal relieved 

 conjunctivitis. He prophesied the general use of the Microscope 

 in medicine. 



10. He made a number of observations which, while not in 

 themselves completely accurate, preceded the more striking and 

 epoch-making observations of the great classical microscopists. 

 Thus he saw the oil globules of milk, and noted that they were 

 more distinct when the milk was sour. He was probably the first 

 to apply the Microscope to the early stages of the development of 

 the chick, in whose embryo he was able to see parts invisible to 

 the naked eye. He distinguished the separate teeth and beautiful 

 pattern in the radula of a slug, and in the " horns " of the same 

 animal he saw the eyes. It has already been explained that he 

 probably was the first to see the blood corpuscles. In an observa- 

 tion on the blood of fever patients he suggests that these corpuscles 

 are little worms and the cause of the fever. He saw similar cor- 

 puscles in the serum exuded from wounds and in the discharges of 



