Y6 NATURAL SCIENCE [February 



ovary is peculiar in structure, and unlike that of most other insects. 

 Instead of a few long ovarian tubes opening together into the 

 oviduct, PJialacrocera possesses many short follicles opening along 

 the tube. This arrangement seems adapted for the simultaneous 

 discharge of the eggs. The pupa is comparatively active in its 

 habits, grasping aquatic weeds with its dorsal hooks, so as to keep 

 the prothoracic respiratory tubes at the surface of the water, or 

 floating freely. Unlike the larva, the pupa is killed by submergence 

 ior a few hours. 



'The Pioneers of Natural Science' 



In his presidential address to the ninth annual meeting of the 

 Association of Economic Entomologists, Mr F, M. Webster discusses 

 the value of systematic work in natural science, comparing the 

 species-makers to pioneers who make possible the progress of the 

 army of biologists who follow. We fear there is some truth in his 

 suggestion that the pioneers are not all as well trained as they 

 should be, and that they waste much valuable time and energy in 

 disputing among themselves, " one faction having no sooner con- 

 structed a portion than another faction tears it down and builds 

 after its own ideas." Proceeding to discuss the prospects of economic 

 entomology in America, Mr Webster utters a needed protest against 

 scientific appointments being bestowed according to the party politics 

 of the applicant. 



Artificial Ants' Nests 



Mr Charles Janet, whose work on the social Hymenoptera has been 

 often mentioned in Natural Science, has published {M^ni. Soc. ZooL, 

 France, x., 1897, pp. 302-323, pi. x.) full descriptions, with figures, 

 of the artificial nests which he has used for his observations on the 

 habits of ant colonies. He obtained the best results with blocks 

 of plaster, provided with suitable hollows covered with a sheet of 

 glass. No earth is needed with this form of nest, and a proper 

 degree of moisture is ensured by pouring water into a tube sunk in 

 one side of the plaster block. 



Catching Plankton 



There is an interesting short paper in Science {Sid December 1897), 

 by Mr Charles A. Kofoid of the Illinois Biological Station, " on 

 some important sources of error in the Plankton method." It is of 

 interest mainly to those who examine the organisms of drinking 



