232 PKOGKESS OF MICROSCOPICAL SCIENCE. 



Approval of Col. Woodward's efforts. — The Medical Society of New 

 York has recently passed a resolution expressing its interest in, and 

 appreciation of, the microscopical work of the United States Army 

 Medical Museum at Washington. The Society ajiproves, with some 

 degree of enthusiasm, the methods of investigation and of disseminating 

 results, employed at the Museum, especially in regard to the study of 

 healthy and diseased tissues ; believing that the progress attained is 

 of material use to the profession, and that it would be unattainable at 

 present without the unusual facilities furnished by the Government. 

 We regret that America is so far ahead of this country in this respect, 

 but we cannot avoid thanking Dr. Woodward for the great value of 

 his laboiu's and for the courtesy with which he treats all micro- 

 scf)pists in his own country and in this. 



Parthenogenesis in the Pupce of Insects. — There appears on this 

 subject an able paper, by M. 0. Von Grimm, in vol. xv.. No. 8, of 

 the ' Memoirs of the Academy of St. Petersburgh.' It is a curious 

 instance of Parthenogenesis in a species of the dipterous genus Chiro- 

 nomus. Like the well-known case of Miastor, discovered by Prof. 

 Wagner, this is an example of reproduction by an insect in one of its 

 preparatory, and therefore sexless stages, called Pcedogenesis, by Yon 

 Baer. The formation of the egg-like reproductive bodies commences 

 in the larvae ; but the eggs are not extruded until the insect has 

 passed into the pupa state. It appears that in the spring the larvae, 

 produced in the ordinary way from eggs, grow rapidly, and after the 

 third change of skin attain their full size and show distinct traces of 

 the pupa within them. The eggs are produced direct from the pupa 

 in this condition. In the autumn the coiu'se of development during 

 the preparatory changes is precisely the same ; the pupa, however, 

 changes into the imago, which deposits the eggs, probably after copu- 

 lation, in the ordinary manner. The mode of development of the 

 eggs and ovaries, and that of the embryo in the egg, are described 

 by the author at considerable length, and illustrated by good figures. 

 The eggs are developed in the same way, both in the sj)ring and in 

 the autumn, although in the one case they will be deposited by the 

 pupa, and in the other by the imago ; and as they present no differ- 

 ence in their structure, the author regards them all as eggs, and 

 rejects the distinction into ova and pseudova. He seems inclined 

 to adopt the notion that the supposed cases of Parthenogenesis may 

 be due to self-fecundation, 



TJie Regeneration of Epitlielial Formations has been lately investi- 

 gated by Herr Julius Arnold. He has sought to establish experimen- 

 tally the source of epithelium in the formation of new skin from 

 granulating wounds. His observations were made upon the cornea, 

 the tongue^ and the epidermis (web) of the living frog, and ujDon the 

 mucous membrane of the hard palate, and upon the scalp of the dog. 

 Arnold failed to confirm the prevailing notions regarding the forma- 

 tion of these cells, by scission of pre-existing epithelial cells, or by 

 genesis from connective-tissue structures. In precisely those points 

 in which the regeneration of epithelium was most active, epithelial 



