WHERE DID LIFE BEGIN? 73 



has made t"he effort, we examine its feet with the microscope, we shall 

 perceive that the interspaces between the hairs are filled with dust. 

 After it has rubbed its feet against one another for a short time, and 

 has passed its wings over them, the dust will be found to have dis- 

 appeared,''and it will again be able to walk on glass. The object of 

 this labor, which flies may be observed to be performing at every 

 moment, is not, then, as was once supposed, to cleanse the wings, but 

 to keep the feet in good condition to stick on smooth surfaces. The 

 wings are supplied with a kind of rough hairs that may very well fill 

 the place of brushes. 



Blackwall believed that flies cleansed their feet for the purpose of 

 removing the superfluous viscous liquid from their pilro. If this were 

 the case, all the parts of the insect that touched its feet would shortly 

 be covered with that substance ; and, if it does not dry but becomes 

 gelatinous, the fly would collect all the dust with which it comes in 

 contact, and would soon look like a lump of dirt. Contrary to this, 

 we know that flies are always clean. 



Other insects that can walk on glass like flies have also, like them, 

 little hairs with club-shaped terminations on the bottoms of their feet, 

 and adhere in the same way. The accompanying illustration (Fig. 3) 

 represents the end of the foot of a beetle (the Polydrosus sericeus), and 

 shows that it is provided with all the appurtenances we have been de- 

 scribing. 



I think I have proved by my experiments that the faculty possessed 

 by flies of walking over polished bodies should not be attributed to a 

 viscous liquid, but simply to capillary action. Even if this liquid, 

 which causes the hairs to adhere to the polished surface, were nothing 

 but pure water, the flies would be able to support themselves upon it, 

 whatever position they might be in. — Translated for the Popular 

 Science Monthly fro^n La Nature. 



■4«» 



WHERE DID LIFE BEGm?* 



By G. HILTON SCEIBNEE. 



THE subject of the distribution of plants and animals has for a long 

 time engaged the attention of many able, persistent, and dis- 

 criminating investigators. Much time and effort have been expended 

 in simply observing and describing the various means by which they 

 get about from place to place. The methods and means by which the 

 seeds of plants are carried and deposited in new localities, the agency 

 of insects, birds, and other animals in their distribution, no less than 



* Preliminary portion of the author's monograph upon this subject published by 

 Charles Scribner's Sons, New York. 



