May 9, 1913] 



SCIENCE 



715 



ure of a mayfly nymph (from Parker & Has- 

 well) on page 399 ; also the confusion of the 

 lettering in figure 32 on page 79 (from 

 Bessey), and the use of the word ovary with 

 very different meaning in this fiigure and in 

 one on page 244. 



Biological pickles do not seem, as a rule, to 

 excite much enthusiasm on the part of a be- 

 ginner of high-school age and exception may 

 be taken, therefore, to the suggestion on page 

 389 that for practise with insects " a mixed lot 

 preserved in wood alcohol or formalin is best." 

 But, as a rule, the suggestions as to labora- 

 tory methods are excellent and the book, as a 

 whole, is a valuable contribution to the litera- 

 ture of biological laboratory methods. 



James G. Needham 



Cornell University 



TEE SO-CALLED AEEOSTATIC BAISS OF 

 CERTAIN LEPWOFTEEOUS LAEV^ 



In his valuable report on the dispersion of 

 the gipsy moth,^ Mr. A. F. Burgess empha- 

 sizes the very great role which is played by the 

 wind in distributing the first-stage caterpil- 

 lars. In this connection he calls attention to, 

 and figures the so-called aerostatic hairs aris- 

 ing from tubercles in first-stage larvas of the 

 gipsy moth, though he does not commit him- 

 self to the theory that they, with their globu- 

 lar swelling at the base, actually aid in ma- 

 king the caterpillars more buoyant. 



These peculiar hairs, to be found on first- 

 stage larvae of the nun moth, as well as of the 

 gipsy moth, were first described by Wachtl 

 and Kornauth" under the name of aerostatic 

 setse, while they designated the balloon-shaped 

 swellings as aerophores. They have been sub- 

 sequently noted by several workers. 



As indicated by the name, the aerophore 

 was supposed to be filled with air, and 

 Wachtl and Kornauth believed that the aero- 



^Bull. 119, Bu. Ent., U. S. Dept. Agric, Feb- 

 ruary, 1913. 



''Wachtl, F. A., und Kornauth, K., "Beitrage 

 zur Kenntniss der Morphologie, Biologie und 

 Pathologie der Nonne (Psilura monacha) ," Mitt- 

 heilungen aus dem forstlichen. Versuchsvesen Oster- 

 reiehs, XVI,, pp. 1-38, 1893, 3 pis. 



static bristles presented a collection of bal- 

 loons which function as an aeronautic appa- 

 ratus. If their interpretation be correct, it is 

 obvious that in both the nun moth larvae and 

 in the gipsy moth larvse these structures play 

 a very important role in aiding the dispersal 

 of the species by the wind. 



Those who hold to the view that the swell- 

 ings are in reality aerophores have not sought 

 to explain how it is that the almost micro- 

 scopic structures should serve as " balloons " 

 if they are filled with air. A balloon rises be- 

 cause it is filled with gas lighter than air. 

 To be sure, Fernald' suggests that they are 

 distended with air " or gas," but it is difficult 

 to conceive of a possible source of a special 

 gas. 



Apparently, Professor Cholodkovsky was the 

 first to suggest the true nature of the so-called 

 aerostatic hairs. First, in a Eussian forestry 

 journal and then in Tubeuf's Zeitschrifi' he 

 called attention to certain serious objections 

 to Wachtl and Kornauth's hypothesis. The 

 fact that the swellings, or vesicles, shrink in 

 dead larvae, militates against the view that 

 they are filled with air. On the contrary, it 

 favors the view that they contain a fluid 

 which, after the death of the larvse, naturally 

 must dry up. In larvse preserved in alcohol, 

 air-filled organs would soon lose their air con- 

 tent, but these vesicles remain for months as 

 full and rounded as in the living larvs. If 

 such a preparation is allowed to dry on the 

 slide all of the " aerophores " quickly shrivel. 



Cholodkovsky, therefore, suggested that the 

 swellings were not filled with air, but with a 

 fluid, and that very probably this was a poison- 

 ous one, since the larvae, in this stage espe- 

 cially, need protection against insectivorous 

 birds. This view was confirmed by the study 

 of sections, which showed a large, unicellular 

 gland underlying each of the " aerostatic 

 bristles " and opening directly into the cavity. 



^ Rept. on the Gypsy Moth, Mass. Board of Agr., 

 1896, pp. 300-301. 



* Cholodkovsky, N., ' ' Ueber die sogenannten 

 Aerophore der Nonnenraupe, " Forstlich-natur- 

 wissenschaftliche Zeitschr., III., pp. 240-243, 1894. 



