448 THE POPULAR SCIENCE MONTHLY 



the life-processes, those of us who had the misfortune to live and ex- 

 haust our greatest enthusiasm during the romantic and morphological 

 periods, can, I suppose, do nothing better with the meager remnant of 

 our vitality than pray for breadth of sympathetic vision on the part 

 of our younger, more numerous and more vigorous contemporaries. 

 The splendid achievements of the investigators who assemble here every 

 summer certainly whet one's desire to see experimental work of the 

 same character accomplished in parasitology. A certain amount of 

 simple experimental work on social parasitism in ants has been inaug- 

 urated by Wasmann and myself and continued with interesting results 

 by Santschi, Emery, Viehmeyer, Donisthorpe and others, but more im- 

 portant work, having for its object the artificial production of individ- 

 ual parasites and such studies on the behavior of their descendants as 

 those recently made by Kammerer on the offspring of Amphibia, whose 

 breeding habits had been artificially modified, have not yet been 

 undertaken. Here again, as in so many other cases, the botanists are 

 blazing the trail for the zoologists. The familiarity of the former with 

 grafting, which is merely an artificially induced parasitism, has led 

 them to undertake interesting experiments, like those recently pub- 

 lished by Pierce 19 and MacDougal and Cannon. 20 And although these 

 experiments yielded less striking results than might, perhaps, have 

 been expected, they nevertheless emphasize an important fact, which all 

 biologists, except systematists and paleontologists, are too apt to over- 

 look, namely, the extraordinary stability of specialized characters. 



Experimental zoologists, including the students of animal behavior, 

 are most keenly interested in the modifiability of the organism, and 

 their experiments are usually devised for the special purpose of de- 

 termining the amplitude and peculiarities of this modifiability. The 

 entomologist, however, who is attempting to use parasitic insects as 

 tools or implements in controlling the depredations of other insects, is 

 primarily interested in the stability of structure and constancy of be- 

 havior. This follows from the very nature of his work. As the essen- 

 tial excellence of a tool consists in its remaining the same as it was 

 when it left the hands of the manufacturer, so a parasitic species can 

 be used as an efficient tool only if it behaves generation after genera- 

 tion with uniform constancy. Hence in combating pests, only those 



gists in our own country during the period characterized by a very exclusive 

 occupation with morphology in our universities : Eiley, ' ' Parasitism in Insects, ' ' 

 Proceed. Ent. Soc. Wash., II., No. 4, 1893, 35 pp.; Webster, "Insect Parasites," 

 15 pp. (reprint without date); Osborn, "Insects Affecting Domestic Animals," 

 Bull. No. 5, U. S. Dept. Agric, 1896, 302 pp., 170 figs.; Howard, "A Study in 

 Insect Parasitism," Tech. Ser. No. 5, U. S. Dept. Agric, 1897. 



18 "Das Eindringen von Wurgeln in lebendige Gewebe, " Botan. Zeitg., III., 

 1894, pp. 169-176; "Artificial Parasitism," Botan. Gazette, XXXVIIL, 1904, 

 pp. 214-217. 



20 "The Conditions of Parasitism in Plants," Carnegie Inst. Publ., Wash- 

 ington, 1910, 60 pp., 10 pis., 2 text-figs. 



